THE WEST Hampstead cafe comes alive when Tigger bounces into the room, all big hellos and happy-smiley hugs.

But within two minutes the wide-eyed creature morphs into a gloomy, droopy Eeyore, indeed one whose tear ducts seem to be working overtime.

Both creatures inhabit the head of Gail Porter, the television presenter who has been rarely out of the headlines since she fronted children's TV back in the early nineties, appeared naked on the Houses of Parliament (digitally), on a range of reality shows and in the tabloids with relationship break-up headlines. (She's divorced from musician Dan Hipgrave).

Porter also revealed she's bi-polar. But what the Edinburgh-born presenter has done consistently is show her Tigger face to the world. In a bid to appear in control (and perhaps not scare the horses in the form of TV and theatre producers) her interview mantra is "I'm fine". For years she's been selling the world a brave face. Now, at 43, and over a three-hour chat, she admits she's been selling a pup.

The openness emerges when we talk of our first interview, 20 years ago when she broke into TV. She was upbeat, fun, at the time, but a little fragile?

"Too right I was," she says. "Before going to college I worked in an Edinburgh B&Q on a Sunday, in the hardwood department and I had to wear a red dress, tan tights and a badge which said 'Gail Is Happy To Help'. The truth is, I wasn't. When I heard the ding dong call on the Tannoy asking me to go to aisle 3, I would think 'I'm getting £3.70 an hour and I'm wearing a red dress - you can f*** right off!' Then I would call my mum and say 'Mum, you need to get here quick - there's been an emergency!' So she'd drive miles in a panic, and say 'What's up?' And I'd say 'I'm bored. Just stay and talk to me.'"

But why go into ephemeral world of television? Surely this was the wrong line of work for someone so up and down, indeed once so depressed she was sectioned? It transpires Porter never planned to step on to the showbiz carousel. "I wanted to become a film editor but one night I was baby sitting for a TV producer who said 'Come and audition' and I did, for an ITV show. And I got offered one job, which sort of led to another."

Porter's career raced ahead - she proved to be spikey and clever - and it included going a stand-up.

However, in 2005 her hair fell out caused by alopecia totalis. In interviews, she claimed to be accepting, and even made light of the condition. But now when she talks of her role in new theatre comedy show, Whingeing Women, which takes a lot of funny/sad female tales and weaves them into a showcase, you learn this was simply great acting on her part. Porter has written a piece for the show about her baldness and her funny, sad, revealing story is a stand-out.

"My favourite recent question was in an interview I did," she says, quoting from the piece.

"The interviewer, whom I won't name, but will say her name rhymes with Dorraine Smelly, asked me; 'Any advice for someone who wants to get their hair back?' Now, I just looked at her and thought 'How can I give advice? I'm bald, for God's sake!'"

Did she ever embrace hair loss? "No. I pretended I did because my mother was dying," she admits. "I didn't want her worrying about me. But I'd go home and have a good cry. I wondered if I'd been some really evil person in a past life to deserve this. Your friends say it doesn't matter, but it does to blokes."

Tears form as she speaks; "I watched this TV dating show TV recently and a young guy was asked his worst dating fear, and he said 'If I was matched with a woman and she had no hair'." Porter adds in soft voice: "The worst thing baldness causes is loneliness."

Porter lives in a flat on her own, seeing her 12-year-old daughter Honey at weekends. She has lots of friends yet she won't go to their homes for dinner. ("I'm not in control in someone else's house"). She reveals she's spent the most part of the last three weeks in bed, depressed, with her sheets raised up like a tent, yet managing to write a great deal, for a new autobiography.

"I write but then discard a lot of the material," she says. "I'm like a child with ADHD. And I get very manic. But then I read some of the discarded material, and I think it's quite good."

How low does she get these days? "I went to the doctors not so long ago, on my knees and in tears. I told him how bad I was; I didn't have my mum and my brother and dad were away.

"I said I didn't want to put this on my friends and begged him to help me. He said: 'We've got a three-month waiting list. Will that suit?' I said 'Hang on. Let me check my Death Diary. Oh, yes, three months? Yes, I'm still hoping to be alive then'."

The presenter infuses her bleak world with black humour, revealing real insight into the world of the bi-polar (and, yes, she has tried all the drugs), the extreme mood swings all worsened when her mum died of cancer in 2009.

Bipolar sufferers can also experience extremes of sexual behaviour. Did she? "I can't comment," she says, grinning then adding; "I went to a sex addicts' group. And when we came out everyone was really horny. It's like 'Do we go for a burger afterwards - or back to someone's home'. The girls ended up having to go to a female only group."

Is writing her book - and for the stage show - cathartic? "Sometimes. But sometimes I write about things and I cry my eyes out and want to chuck everything out of the window. Being bipolar is great when you're up. But it's exhausting."

Porter is famous but, as she admits, cash-strapped. She once had the big house in Bellsize Park but that disappeared with her marriage. Work has appeared over the years such as documentaries on prostitution, and reality television shows in which she joined a hospital A&E ("The TV company knew I'd bawl my eyes out, and they were right.") But being bald limits TV opportunities. How does she survive? "It's hard," she says, with a wry smile. "Sometimes I'll offer myself up for work to local estate agents or Boots. But they don't think I'm serious."

Over the years, there have been several relationships, but they tend not to last; Porter admits her changing moods mean ever-changing needs. "Sometimes I need to be on my own. Sometimes I really want a cuddle." She breaks into a laugh; "I go to the cinema on my own every week and there's always a fat bloke in the corner with a big bucket of popcorn and he always says 'All right, Gail!' That's the highlight of my single life these days."

But no sooner has the laugh subsided, her Eeyore returns. "Sometimes I go out and talk to everybody. Sometimes I wear a baseball hat and want to hide." The hair issue is always present. Porter reveals a recent story about a white van man who switched his window down and screamed out 'Hey, Baldy!' "However, he drove up to a red traffic light so I had the pleasure of going up to his window - he couldn't even look at me - and called out 'Oi, t**t. It's me. Baldy. Wind your window down will you? In fact, why don't you step outside your van?' Fortunately for him, the lights went to amber and he sped off."

Porter's book will be great. Over lunch she shares stories about Robert De Niro, about shocking Leo DiCaprio and singing Summer Love with John Travolta - and explains why she allowed a voodoo witch doctor to tattoo her. She opens up about her life, from stardom to skintdom. She talks about the charity work sadness of children with cancer and she cries as she talks.

But she's great fun to be with, writes terrifically and laughs just as easily as she cries, highlighted when asked what she really wants out of life.

"I'd like someone to go to the pictures with," she says, Tigger-grinning. "Otherwise, it could end up with just me and the fat bloke with the popcorn."

Whingeing Women, the King's Theatre, Glasgow, October 9-11