He doesn't drink. He's mates with Tom Cruise. He's cagey about who's in the new Star Wars film. Has Simon Pegg gone a bit Hollywood?

Pegg discusses life off the booze, the end of his 'Cornetto Trilogy' and why his friend JJ Abrams really shouldn't cast him in the new Star Wars film

Here comes lyin' Simon Pegg, confidant of major Hollywood players, blithely prepared to dissemble to the little people to protect his A-list pals. The big kid who thrilled us in stoutly British TV and film comedies Spaced and Shaun of the Dead? Man, he's changed. As good pal Tom Cruise would probably attest.

To explain: the last time I met Pegg, in summer 2011, on the set of last year's misfiring indie comedy A Fantastic Fear of Everything, I'd asked the actor/writer if the rumours surrounding JJ Abrams' second Star Trek film were true – that Benedict Cumberbatch had been cast to play that old foe of Kirk and co, Khan.

"It's not Khan," Pegg replied, firmly. "That's a myth. Everyone says it is, but it's not."

I knew Pegg (who plays the USS Enterprise's chief engineer Scotty in the hugely successful reborn franchise) was close to director Abrams. So, I pressed, was his denial of the identity of Cumberbatch's character deliberate misinformation? "No, I think people just want to have a scoop," he said. "It annoys me – it's beyond the point to just ferret around for spoilers all the time and try to be the first one to break them."

As I thought at the time: that's a bit rich coming from this ur-fanboy and author of an autobiography called Nerd Do Well. Pegg knows better than most that geeks want any scoop, on anything, any time. "It just spoils the film," he frowned. "It masquerades as interest in the movie but really it's just nosiness and impatience. And you just wanna say, 'Oh fuck off! Wait for the film! You'll find out in a year!' It'll be there, on the screen, and it'll be a nice surprise."

In 'Hot Fuzz', the second in the 'Cornetto Trilogy'

So it came to pass that I waited. And lo, Cumberbatch was Khan.

"I famously denied that, yes!" he laughs when we meet over morning coffee in a Thames- side hotel in London. "Knowing that I was lying!" Pegg winces. "But it was a defensive lie. I was protecting the sanctity of the story!" he hoots.

Which, I suppose, is fair enough, and also appropriately geekish. And for sure, I enjoyed Star Trek: Into Darkness all the more when Cumberbatch's none-more-saturnine character's true identity was revealed. But now that Pegg is on the back foot and in mea culpa mode, I press home my advantage: what can he tell us about Abrams' next sci-fi epic reboot, Star Wars: Episode VII? "Well, JJ is a friend," the 43-year-old begins, "and interacting with him, I do hear stuff, and I'm very excited. I can't think of anyone better for the job. He cares about it."

He does say that Abrams is in the UK right now, in pre-production on Star Wars in advance of next spring's commencement of shooting at Pinewood Studios outside London. And that, by the by, the director/producer is not relinquishing Star Trek duties completely – the American has been in talks with Joe Cornish (of Adam & Joe comedy repute, but more pertinently, director of Attack the Block) about the Londoner helming the third instalment of the recent series.

"And people are saying to me, 'Oh, are you gonna be in it, are you gonna be in Star Wars?' In all honesty, I feel it would be detrimental to the film. And that's not me being self-effacing," Pegg adds hastily, ever caught between discussing the realities of his stellar career and the desire not to sound bumptious. "I think what JJ will do is cast new people. And not do any stunt-casting. In this day and age where there is this cult of celebrity, if someone crops up in a film and you go, 'Oh it's them,' it is gonna pop the end of the film."

Surely this fanatic fan of the first three Star Wars films (but not so much of the second three) could manage an undercover role? Boba Fett's cousin? Or an Ewok? "Ha ha!" he laughs, quickly (I think he had a Stormtrooper in mind). "Well, the very fact that I'll be shooting when it's being shot precludes me being in it. But I'll visit the set – I will definitely go down, hopefully on a day that, if the original cast do turn up in it, Carrie Fisher is there." Ah-ha! Let's take it from that aside that Fisher, Mark Hamill and Harrison Ford do make an appearance in Episode VII.

Oh, and that film Pegg will be working on at the same time as the Star Wars shoot? The much-anticipated Mission: Impossible 5, with The Cruiser. In the follow-up to Mission: Impossible – Ghost Protocol, Pegg will be reprising his role as superspy Ethan Hunt's techy sidekick. That fourth instalment took a massive $700m globally. There are worse scheduling clashes, one imagines.

I tell Pegg that M:I5's release date has just been announced. It's coming out at Christmas 2015 – one week before Star Wars. "Is it?" he replies, genuinely surprised. "Shit! Oh that's interesting. Ah well, we'll be number one for a week!"

Sobriety chimed with Pegg's ceaseless ambition (David Vintiner)

But forget all that blockbuster movie, tentpoles-at-dawn jostling. We're here today to discuss a passion project that's a lot closer to home: the completion of the trilogy of British comedy films made by Pegg and his fellow Spaced alumnus, co-star Nick Frost and director/co-writer Edgar Wright. This month sees the release on DVD of The World's End. On one level, it's a very funny, midlife-crisis-with-extra-swearing comedy. It's not so much a road movie as a crawl movie: small-town saddo Gary King (Pegg) corrals his much more successful (and much more grown-up) school friends for an attempt at a drinking session round the fabled Golden Mile: the 12-pub circuit of their gilded(ish) youth.

It's joined on the shelves – just in time for Christmas – by a box set that also features its two predecessors, Shaun of the Dead (2004) and Hot Fuzz (2007). After we've finished speaking, Pegg has to sign a pile of slipcases for the boxset. He points to a line of type on the packaging: "The Three Flavours Cornetto Trilogy". That rubric is a movie buffs' tweak on Krzysztof Kieslowski's Three Colours trilogy, and a reference to one of the running visual gags linking the three films. But up until now it was only the unofficial title yoking the troika of films about killer zombies, murderous neighbourhood busybodies and, in The World's End, bodysnatching aliens.

"There was a big old creative meeting cos Cornetto wanted to have that in their own writing," he notes wryly. Did they need permission to give the boxset that title? "Yeah, there was some weird wrangle," he mutters.

In spring, shortly after completing the final nips and tucks on The World's End, Pegg admitted to a "sense of ennui" now their decade-in-the-making, critically acclaimed, box-office-thumping trilogy was complete. What does he feel now? Weary triumph? Post-coital slump?

"Probably the post-coital slump! But if that's the case, it was a really good session! No, I feel very happy. There was a great sense of incompletion with Spaced because we never did the third series. With this, we've done what we set out to do – not that we set out to make three films when we started Shaun…" It was only halfway through Hot Fuzz that Pegg, Frost and Wright realised they could make a trilogy with a "thematic" connection. Which was?

"All three are about the loss of identity, having to give your self over to a larger, homogenising force." Those forces being zombies that want to eat you, villagers who want you to conform (or be killed), "and with The World's End it's this very insidious force of indoctrination. It's the illusion of choice. But really we're being very subtly manipulated into being consumers. What's happening to Earth in The World's End is kind of what's happening to our high streets."

With Nick Frost and Paddy Considine in 'The World's End'

For Pegg – raised in Gloucestershire, and formerly based in London, but now located in the posh exurbs of Hertfordshire with his wife and their four-year-old daughter – the change is apparent. "Every village and every town is becoming like a mini-London, populated with these chains, pubs are becoming Wetherspooned, and a certain identity is being lost."

That said, he chuckles, "We're not necessarily saying in the movie that that's all bad. We want it to be a bit confusing. Maybe we should be controlled a little bit. Maybe that coffee shop that was there before Starbucks was shit!

"Although," he adds, "I'd say less so with the pubs thing. That family-run, cosy little boozer is being threatened by a more corporate identity which isn't anywhere near as charming."

Pegg says this from the vantage point of a non-drinker. He's been teetotal since turning 40. Does this keen snowboarder and gym bunny see himself as being off the booze for ever? "I don't know. I'm kind of really enjoying it. Now I've got a bit of distance from it, I feel like I don't wanna go back to it in a way. Maybe it's because when I go out with my friends now – and this was a revelation to me – round about 10 o'clock I start looking around me and thinking, 'Everyone's an arsehole! When did this happen?'

"And I realised I probably was as well when I was drinking…" He smiles, and shrugs. "I don't really like being around drunk people any more. So I'm kinda happy not to be part of that.

"And I'm not looking down on it," he insists, lest we think he's caught the holier-than-thou, puritanical zombie-ism that is endemic in a particular stratum of Hollywood life, "cos I remember the joy of it. But I feel like, 'Ooh, I may have dodged a bullet there.' It wasn't enhancing my life in any way – that's kinda why I stopped. It wasn't making me healthy, I was a dad, I wanted to be present in the mornings…

"And I'm the kind of person that would… I… I'm…" he stutters. "I've got to do all or nothing. It can't just be a glass of wine with dinner. I'd wanna go out and get beered up again. And I'm happy to be saved from that."

Pegg certainly has a lot going on: 'I did 127,000 air miles this past year' (David Vintiner)

Sobriety also chimed with Pegg's ceaseless ambition – he wants to write, he wants to act, he wants to appear in blockbusters, in indie films, in TV dramas. He likes to be productive. And productive in the right way. Of his, Frost and Wright's well-crafted, joke-a-minute scripts, "People always say, 'Oh did you think that up in the pub?' You never have good ideas in the pub! Unless you're someone like Shane MacGowan! Or someone for whom it is a creative fuel. I wasn't funny when I was drunk or stoned or whatever. So, yeah, not drinking is definitely an aid to creativity."

Pegg certainly has a lot going on. Early next year he shoots Man Up, a British romcom, followed (he hopes) by another UK film, a project with former Python Terry Jones. Then, straight into Mission: Impossible 5. He'll also be seen in cinemas in Hector and the Search for Happiness, a globe-trotting film that saw him shoot in China, South Africa, Canada, America, Tibet and Britain. His is the title role, a kind of Buddhist Forrest Gump. And in 2014 we'll see his portrayal of a "mercurial" assassin in "very darkly humorous" crime thriller Kill Me Three Times, which he made in Australia. "I did 127,000 air miles this past year," he says, wearily but not without a little pride.

More immediately, on American TV next month, Pegg pops up in the opening episode of Mob City. It's a noir-ish period drama series set in 1940s Los Angeles. The man behind it is writer/director Frank Darabont (The Shawshank Redemption), televisual creator of another sensational and hugely successful zombie project, The Walking Dead. Mob City sounds as much like a sure thing as you can get in TV these days. And it offers a rare, down-the-line "straight" acting gig for Pegg. "Even though, ironically, I'm playing a comedian," he smiles. "Which was great fun."

It's not a leading role by any means. But, if it gets the green light for a second series, might Mob City offer Pegg the opportunity to join fellow Brits Damien Lewis and Rupert Friend (Homeland), Jonny Lee Miller (Elementary), Matthew Rhys (The Americans), Andrew Lincoln (The Walking Dead), Charlie Hunnam (Sons of Anarchy) and Kevin McKidd (Grey's Anatomy) with a recurring role in a quality US drama?

"Um," he squirms. "I can't say… And I'm not gonna lie to you – again!"

'The World's End' is out on DVD tomorrow