I don’t like getting up too early unless I have to. When you’re filming and you’ve got prosthetic make-up on, which doesn’t happen often. You have to be up before you’ve gone to bed, at 2am, to sit in make-up for six hours. That’s the worst. But as I’m not filming at present I’ll get up at 8.30. I shower using Ren products, a face and body wash — I liked the packaging — and I’ll dress in loose-fitting clothes, shorts and a T-shirt, before making breakfast and watching Sky News.

I have organic porridge with milk. When I was training for the swim across the Channel in 2006, that was the best breakfast; it’s a slow release of carbohydrates, so you don’t get hungry. I add blackberries and honey from my local deli, Melrose and Morgan in Primrose Hill, and drink peppermint tea.

Work normally means Matt [Lucas] coming over to my house about 10am. We’re writing at the moment. We’ll chat for a bit before going to my study. One of us will have an idea for a sketch, we’ll talk about the characters and when we feel we have enough we’ll start writing and improvising, so stuff can pour out. You’ve to be disciplined — we haven’t a boss who’s checking up on us — otherwise you could just sit and chat. We work office hours, even bank holidays, unless we’re filming or have other commitments. For 100 sketches in a series we’ll write 160, then dispense with the ones we won’t use. It can be heartbreaking after the hours you’ve spent, but that’s the nature of sketch comedy.

Matt and I met at the National Youth Theatre in 1990 and started doing shows together in ’95, at the Edinburgh Fringe festival. We know we’re onto something if we’ve made each other laugh, and that’s a really special moment. It’s not always like that, but we’re comfortable enough with each other that we can be honest and go: “No, that doesn’t work.” Some days you’re not in the mood to be funny or something’s going on in your life that’s traumatic — like writing when my dad was dying of cancer, or when Matt was separating from his partner.

I remember writing for a couple of days between when my dad died and his funeral — didn’t know what else to do. It felt surreal. You think: “Surely I’ve got to be happy to be funny?” But it’s not always the case.

We stop for lunch and sometimes go to Wagamama in Camden, but the last time we were followed by paparazzi, which gets you down — who wants to be pictured eating noodles? You know they’ll get a shot of you with them landing in your lap. So I’ll microwave food from M&S, fish or chicken with vegetables.

We might watch Loose Women before working a few more hours.

When I’m not writing with Matt I work on other projects. My second children’s book comes out later in the year. It’s called Mr Stink. The first one I dedicated to my three-year-old nephew, Eddie. Both books have been illustrated by Quentin Blake, who did the Roald Dahl books; it’s been a thrill to work with him. It’s nice to have things happen where you have to pinch yourself — like 20 years ago reading a Roald Dahl book and looking at those drawings, then one day that person illustrates your work… magical. Or seeing Michael Gambon on stage during a school outing, then years later you’re in a Pinter play together.

At 5 I go swimming in Soho, or Paul Stephen Lubicz, my trainer, comes over. Being Australian, he’s very blokey, and we’ll have blokey chats about women in the way I wouldn’t with most of my friends. He makes me do horrible exercises, but I always feel better after.

Being in all day, I like to go out in the evening and look smart, but not like I’ve come out of the City. I’m a tall, broad guy and look better well- dressed. When I first earned some money, one of the nice things was being able to go to Savile Row and buy a Richard James suit. Beautiful, quite conservative, but you don’t feel as if you’re in a work suit. I’m also a fan of Tom Ford’s clothes.

For dinner I’ll meet friends, like Natalie Imbruglia, who likes Nobu — or if Kate Beckinsale’s in town we’ll go to Scott’s or J Sheekey for fish and seafood. When you’re a single guy it’s great to have some good female friends; Natalie refers to me as her “handbag”! Or I might take my mum to the theatre, as I know she really appreciates it.

I like watching TV comedy shows to see what everyone’s doing. When you see something impressive it makes you work harder. I listen to quite depressing music, Nick Cave or Morrissey, but I’m obsessed with this CD of the actor Tom Courtenay doing a one-man show about Philip Larkin called Pretending to Be Me. It reminds one of what great writing is. I love Larkin’s poems: they don’t try to transcend the commonplace; they’re much more straightforward.

Poetry is great to dip into before going to bed, rather than falling asleep reading a novel and being confused over what you’ve read or not. I haven’t had a good night’s sleep in seven years; unfortunately, I rely on pills. I’ve tried everything. If I could wish anything for myself, I’d wish I could sleep better

David Walliams’s book The Boy in the Dress (HarperCollins, £6.99) is out in paperback this week

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