Simon Amstell is a terrible worrier.
The 30-year-old comedian, who made his name as the wonderfully acerbic host of Channel 4's Popworld and the BBC2 pop quiz Never Mind the Buzzcocks, is currently worried about doing interviews to promote his latest venture – a BBC2 sitcom entitled Grandma's House. "I'd rather be seen as a genius recluse," he says. "The J D Salinger of comedy," his long-term friend and writing partner, Dan Swimer, chips in, as the pair eat lunch in the central London edit suite where they are currently collaborating.
The funny thing is, Amstell has succeeded in parlaying this constant anxiety into a very promising new comedy. In Grandma's House, which he co-wrote with Swimer, Amstell plays a character called Simon (a lot of thought went into that name) who is plagued with doubts about his life. Every week, he goes round to his grandma's (Linda Bassett) house and kvetches to his family, including his overbearing mother (a bravura performance by Rebecca Front) and his sceptical aunt (an equally spirited Samantha Spiro), about the wrong directions he's taking.
In the first episode, his mother is bitterly disappointed that Simon is giving up his high-profile job as the chair of a popular, unnamed pop quiz. "I want to do something more meaningful," he complains.
"You've got a skill already," his mother retorts, "taking the piss out of pop stars." She adds: "You're not lonely – you've met Michael Bublé." Later, Simon expresses his concerns about his mother's obnoxious new boyfriend, an ageing furniture salesman called Clive (James Smith), but she is having none of it. "He's very kind to me, and he's got Sky HD on a 47-inch plasma. You can see every single hair in Noel Edmonds' beard. What more do you want from life?"
"True love?" ventures her son.
Later on, Simon's grandfather (Geoffrey Hutchings) confides in him that he believes he has cancer, but all Simon can think about is how he should react. "How am I doing here?" he asks his grandfather. "I'm going for a concerned, sensitive voice."
Acknowledging the age-old literary principle that "happiness writes white", Grandma's House manages to turn the awkwardness and embarrassment that is the common currency of so many families into highly amusing comedy. The sitcom, which has no laughter track, is a consummately well-acted study of middle-class neurosis. It's what would happen if the vintage Woody Allen ever moved to a nondescript north London suburb.
"Self-deprecation is at the root of what we do," says Amstell, who, like his fictional alter ego, is effortlessly funny and appealingly self-effacing.
"Contentment just isn't funny," he reflects. "'Hello, everything's going rather well' – that's not going to make you laugh. A sitcom about the Dalai Lama would be very tricky to pull off. You'd have to go behind the scenes and reveal that he's actually a bit cheeky. The reality is that we're all going to die, so anxiety is pointless. But that's why it's funny to watch people who are so focused on their own anxiety."
The comedian, who hails from Gants Hill in north-east London, says that Grandma's House was built on the solid foundations of his own foibles. "In the pilot," he recalls, "we didn't write me very well. I had no character, I was the boring voice of reason in the middle, shaking my head whenever anyone else spoke. Then we suddenly realised that it would only work if we used everything that was wrong with me in real life. I had to be the biggest idiot in it. There's a point in the sitcom where Simon's 14-year-old cousin says to him, 'You don't need to come to grandma's house every week'."
Amstell continues: "Simon doesn't have to be always trying to change his family. We're habitual creatures and find it scary to change. But for Simon, it's all about being accepted. He's attempting to heal everything. That's probably a role that started with his parents' divorce. He still has a lot of unresolved issues to address. But I'm not sure about that – I'd have to ask him."
So which of the real Simon's traits does the sitcom Simon share? "The need to try to fix others and myself, ego, narcissism, and attempting to deal with the meaninglessness of existence," Amstell deadpans, before laughing: "We're going very deep here. I thought we'd just talk about fonts and pens!"
The comedian confesses that he had misguidedly hoped that creating a doubt-stricken fictional character would help to alleviate his real-life neuroses – work as extended therapy session. "When you're writing it, you think, 'this is very healing and is really going to help. I'm venting all my emotions here, and I'm now very pleased that terrible thing happened to me because I'm able to use it in my comedy'. Then the filming finishes, and you make the same stupid mistakes as ever. You're still the same idiot."
Amstell adds: "I wore a lot of my own clothes on Grandma's House. At the end of the shoot, I thought, 'I can't be that guy any more', so I bought some new trousers. I imagined everything would be different because I had some new trousers. But it was a case of 'different trousers, same idiot'."
Amstell concedes that he is more than a little alarmed that exposing so much of his real character in Grandma's House will only add to his anxiety. "I suddenly thought, we can't put this on TV – it's so close to me! That had been the aim – to reveal, reveal, reveal. But then I saw it and I thought, 'this is a bit revealing!'"
The comedian did not help himself, of course, by calling the central character in Grandma's House Simon. But that was a very deliberate decision. "You don't want people to have it on in the background thinking, 'oh, this is just another TV show that doesn't connect with real life'. We like to know where people are coming from. With Roseanne, we felt it was her. I didn't want to hide behind another name. I've seen sitcoms where they've changed the name of the person and they don't ring as true as something like Curb Your Enthusiasm or Seinfeld.
"It's more interesting for the audience, too. They're curious about how close the character is to the actor – 'what's he revealing about himself here?' That gives it another level for the audience that wouldn't be there if we just called him 'Tony Anxious Man'."
Amstell is also a compelling live comic whose debut stand-up DVD, Do Nothing, is released in November. But even here he is assailed by uncertainty. "Before every stand-up show, I say to myself, 'why do I need all this laughter from strangers and attention and validation?' I have to avoid focusing on the dysfunction that's at the root of it and remind myself that I love it."
The comedian surprised many when he quit his job hosting Never Mind the Buzzcocks last year, but he felt he could do nothing more with the chairman's role, for which he won two British Comedy Awards and a Royal Television Society Award. "It seemed ridiculous to people that I should leave, but I couldn't have carried on. Being cheeky and naughty is only funny if it's unexpected. It got to the point where I'd say to a guest, 'So, you've got a new album', and they'd reply, 'What are you going to say about it? Yeah, it's shit, isn't it?'"
"I'm only happy if there's an element of discovery. I don't want to be the expert guy who always knows what he's doing. I want to be learning all the time. I like it when people think, 'not bad, considering he shouldn't be here'."
Here's another question that may well trigger more worry in Amstell: would his very successful comedy career be ruined if he ever attained true happiness? "I'd prefer to be happy," he observes. "But happiness can't be a goal – it only exists in moments.
"In Grandma's House, Simon says, 'I'm going to shave my head and go to Thailand' – that's his idea of what he needs to be happy. But if I ever did that, I'd get bored very quickly and really wish I was back doing comedy in London. What's the answer?"
He closes by revealing what he's up to next. "I'm working on a new stand-up show," he says.
"It'll probably be about anxiety."
'Grandma's House' begins on BBC2 at 10pm tonight