Drink, Shop & Do looks like someone's front-room but everything is for sale

In a light, high-ceilinged room, vintage floral teacups chink and cucumber finger sandwiches are being served. Although it spans several decades, the décor goes well with the jaunty Andrews Sisters soundtrack – there's a sun-coloured 1960s wooden dresser, kitsch ceramic swans clustered on its shelves, a fringed standard lamp, a 1950s blue sofa, a couple of well-loved velvet armchairs gathered around a teak coffee table – and underneath, a battered box of Scrabble.

The trio ensconced in this cosy corner – one of whom is knitting – look, literally, at home. Until you notice that everything – from the patchwork blanket one is sitting on, to the glasses in the cupboard and the print by an emerging artist – has a fluorescent star next to it: a price tag.

Drink, Shop & Do, situated in London's King's Cross, is an interiors store with a difference. Not only does the second-hand and new-designer outlet feel homely, it also serves cocktails (from Ginger Rogers to Ruby Shoes) and snacks (the afternoon tea even comes on a cake stand), and hosts a range of quirky activity nights, based around craft – though very loosely (currently popular are "dot-to-dot disco" and "play with clay in a 1980s style" nights, where guests can either recreate 1970s album covers or sculpt their own Lionel Richies, minus blindfolds, while listening to retro tunes).

The relaxed vibe is deliberate. "I'd always dreamt of having a design shop," explains 25-year-old co-proprietor Coralie Sleap, "but in so many of those places you feel you have to be quiet and not touch. I wanted a shop where you could get drunk and make things."

Her business partner – and "best friend since the first day of secondary school" – Kristie Bishop, also 25, had always wanted a pretty sweet shop and her own cocktail menu. "We even had it in our yearbooks when we were 17," says Bishop, laughing. "It was going to be called Kristabella's Beanie Hut."

Et – sensibly minus the name – voilà. The shop opened last August, and has been packed out ever since. Which, if k

it were a small starter shop would be less surprising. But the space is vast and easily seats 50. The building, in a prime location minutes from the station in up-and-coming King's Cross, is a former Victorian bathhouse. Apart from its stint as a 1980s rave venue, "the building's history is mainly sex-industry based", says Sleap (and there's still a sex shop downstairs – signs en route to the loos warn customers not to open the wrong door). The small street-level entrance is deceptive: stairs at the back lead to a giant, columned room, lit by a large skylight window. That leads to the "dome-room" – in which you can imagine a semi-circle of Victorian gentlemen encased, neck down, in steam baths. However did they put it all together?

"After college, when we were doing boring admin jobs," says Sleap, a ceramics graduate, "I used to run 'Art Club' one night a week. It was always something fun, such as making robots. It began with about 10 of us, but then word spread and soon there were about 30 people each week crammed into my living-room." It has become one of the foundations for Drink, Shop & Do.

Sleap went on to become the print sales manager at a street-art gallery, where she gained insight into putting on events and business. But her heart wasn't in it, so she left. Bishop, meanwhile, was working in promotions and events for an alcohol firm, handily with a company car. "The first year was amazing," she says. "But then it was all about doing sales in Dog & Duck pubs. Got a bit harrowing."

At this point, the pair found themselves on a sunny pub bench one afternoon, and "a bit fed up". Talking through their fantasy jobs, they realised their ideas were compatible. "Suddenly," says Sleap, "we thought, 'We could pull this off.'"

Sleap already knew about the building, as she'd put on an event there, so called the landlord. Bishop made use of her company car, credit card and eBay, driving round the country stocking up on second-hand treasures to sell. She also used her drinks knowledge to design the cocktail menu. Sleap's mum was drafted in to make cakes. They agreed to the landlord's suggestion of a trial Christmas pop-up in 2009 – and made a profit. It was enough to convince investors, and in August 2010 they opened properly. It was a big leap, but, says Sleap, "We don't have houses, husbands or babies, and thought, if there's a time to go bankrupt, it's now!"

They are far from that – but how do they manage the stock turnover? With everything for sale, what if someone wanted to buy the huge bar, where all the food and drink preparation goes on? "Oh, we'd be glad," says Sleap. "We like the challenge of thinking: 'That's gone, how do we make that corner look nice now?'"

However, while there is some spare stock in the office downstairs, there was one occasion on which they were caught short: "We had another bar in the dome-room," says Bishop, "it hid our freezer – and someone bought it. That was tricky; we didn't have a spare of those..."

Then again, when they do run out, they get to do their favourite thing: going shopping for vintage gems together. "Sometimes," says Sleap, "we're at a market, looking at something beautiful, and all of a sudden we'll nudge each other, going, 'Look what we're doing for a living!' Then we have a little high five. Then it's back to business. So it hasn't got boring yet. I don't think it will."

Drink, Shop & Do is at 9 Caledonian Road, London N1 ( drinkshopdo.com)