At home in his PJs, tapping out Not Going Out scripts on his computer, Lee Mack tells Gemma Dunn about cherishing his BBC sitcom success

Lee Mack has one big unfilled ambition, and it's not what you'd expect. "I desperately want to be in Doctor Who," declares the 48-year-old. "I'll take a 30-second walk-on part. I've always been a massive fan of the show, me and the kids watch it," he explains, barely pausing for breath.

"The truth is, my children (he has two sons and a daughter with wife Tara) are fairly indifferent about what I do. Occasionally they watch something on TV and raise their eyebrows at me when I tell a bad joke, but they've grown up with it so they aren't too excited. But by God, if I was on Doctor Who, I'd finally get respect off them!"

It wouldn't be the first time king-of-the-the-one-liners Mack saw his dreams come true. "Saying you wanted to be a comedian in the early-Eighties when you lived up North was like saying I want to be an astronaut or a professional footballer, there was no reality based in it," he recalls - and yet, after leaving his home town of Southport for London back in the early-Nineties, he went on to establish himself as one of the UK's most recognisable and celebrated comics.

Known for his finely crafted one-liners and quick ad-libs, the infectious star - full name Lee Gordon McKillop - has packed out theatres with his live stand-up shows, tickled audiences with his laugh-a-minute TV sketches, and can currently be seen on comedy panel shows Would I Lie To You? and Duck Quacks Don't Echo. But today's chat is in favour of a project much closer to home: Mack's brainchild, Not Going Out.

"Hi, it's Lee Mack!" he booms down the line when I call him. I'd expected an assistant or PR person to answer - and, registering my surprise, Mack adds: "Who were you expecting, Michael McIntyre?"

He says he's surrounded by boxes, having just moved house, but aside from the odd background shuffle, you wouldn't know. He's all ears, stress-free, and while there are less one-liners than you'd expect from his on-screen persona, he's brilliantly funny.

Not Going Out - the multi-award-winning BBC One series about chaotic couple Lee and Lucy - is back for an eighth run (with a ninth and 10th also confirmed), and for Mack, co-writer and mainstay lead, it's a blessing.

"It's exciting because it means we can really plan without having to worry if people are free," he says. "This is my favourite thing that I do; it's nothing but joy. But once the reality of sitting down in front of a computer kicks in, I'll be like, 'Oh my God, that's a lot of episodes to write'."

He's not really worried. We've changed the format - it's about a wife and three kids, it's about the whole married life thing - so it's arguably more familiar, because that's the reality of my real life. I'm married with kids."

Viewers last saw Lee (Mack) and Lucy (Green Wing's Sally Bretton) as newlyweds, just having their first baby. Now, fast-forward seven years, Charlie is seven years old and has siblings; five-year-old twins, Benji and Molly. Co-written with Daniel Peak and newbie to the show Sarah Morgan, Mack explains the basic rule of thumb when it came to penning the scripts this time round was simple: "If it hasn't happened to us, then forget it".

Is there a pressure to draw more laughs than the last? "I just say or write what I think is funny," Mack retorts. "The idea that it would resonate with somebody else is a nice bonus. In fact, it is essential, because you couldn't do the job if nobody was interested, but it's never the motivation."

And it's never the end product that's most important to him, either, but the process of making it. "I've always seen myself as more of a writer. Some people say there is nothing better than performing and I always think maybe I'm missing something. I like it, but I don't feel a desire for it," he admits. "I'm much happier in my pyjamas with a cup of coffee, writing the scripts in front of a computer."

Despite this, Mack will soon challenge his acting prowess with a West End debut alongside Griff Rhys Jones in The Miser, an adaptation of Moliere's classic comedy. "Yes, talking of not being bothered about performing...," he quips, laughing. "I think that's a different thing because it is my first ever play. I don't mean professionally, I mean ever. I'm a big fan of the writer Phil Porter and the director Sean Foley, so I'm in safe hands, and it's quite a nice change after all these years of driving the ship of the sitcom, to let go and have someone else be in charge."

As for scoping out more serious drama roles elsewhere, Mack isn't sold. "An actor will smell a stand-up comedian; I put myself in that bracket," he says. "The Miser is quite farcical; it hopefully plays to my strengths and is up my street."

With a chuckle, he adds: "I'm absolutely convinced that I can do Doctor Who; did I mention Doctor Who? But proper serious drama? I don't know. Although as I get older, I like to try more and more things that aren't in my comfort zone, so I'm the kind of person that would give it a bash."

With a solid base in the stand-up world, will the comedy circuit always remain his go-to?

"I'll never stop doing stand-up, hopefully, but I haven't got this burning desire to do it all the time," Mack confesses. "The biggest thing that drives me is the sitcom. It has taken up so much of my life in the last 10 years that it's very hard to let go of it now.

"You can tour whenever you want - well you can if you're a stand-up and you've got an audience - but sitcoms are reliant on being commissioned by other people, so I don't want to turn that down," Mack reasons.

"I'm almost certain it's going to end, it can't last forever, and I'll have the rest of my life to tour, won't I?"

Not Going Out is on Fridays on BBC One.