By Hannah Stephenson, Press Association

Fern Britton is looking fit and well, when we meet near the home she shares with TV chef Phil Vickery and her four children.

But having shed stones in recent years, thanks to a gastric band coupled with sensible eating and plenty of exercise, most notably cycling, she's been fit for some time now.

On Friday, she embarks on #Challenge 57, a 1000-mile bike ride, cycling 57 miles a day (a mileage to match her age) from John O'Groats to Land's End, to raise £57,000 for Professor Robert Winston's Genesis Research Trust, specifically for research into miscarriage.

"I'm 57, I was born in 1957, and I want to do something big for that so #Challenge 57 was born." she explains of the challenge.

"I've been in constant training for the last 10 years so I keep it topped up, but in the last six months I've been pushing it some more. I'm doing hills that I couldn't do before. And I'm running two to three times a week."

The exercise also helps stave off the bouts of depression Britton has battled for years.

"I'm not on medication at the moment. I'm doing very well, and maybe upping the exercise has helped."

But she realises the depression could return.

"I'm fully expecting to have another episode. It takes a while to recognise it, but now that I'm experienced in it, I start to recognise the signs, usually when it's a bit too late.

"It's like in the distance you can see a hole in the road, and you know you're going to fall in it. The choice is fall in, walk round or jump over. In general, it's very hard not to fall in, so you go to the doctor and you get some help. The medication is so good.

"Feeling invisible and not looking forward to anything are two big signs. Those are mine. The family is very understanding because I can articulate it to them. "

Her fifth novel, A Good Catch, has just been published, a romantic yarn about the intertwined lives of two couples in Cornwall. It explores the subjects of class distinction, love unrequited, undetermined parentage - and body image.

One of the female protagonists, Loveday, is voluptuous rather than slender and not a conventional fashion-follower, but is an altogether more likeable and desirable character than her slim, well-groomed best friend, Greer.

Britton is contracted to write two more novels, although she likes keeping her toes dipped in the TV world, but not to the same extent as her This Morning days.

"I had a wonderful time doing it and you have to sometimes say you're very satisfied with what you've had and what you've done. I'm lucky to have done it.

"I love television. I still always want a foot in the door. However, I'm sensible enough to know that it will stop at some stage. "

Britton is one of those especially talented interviewers who assumes a cosy, comfortable rapport with interviewees, before slamming them with the killer question.

She admits she would like to have a chance to interview some of the main players in the forthcoming election.

"I'd ask Cameron not necessarily about policy, but about who he is. Whoever we're voting for, we need to know that we like them, that we trust them, that their ideas are based on a sane mind and a just and sincere mind.

"Politicians don't listen to us while they are in power, but as soon as they need our votes, they think we're stupid and are going to trust them. Well, we don't," she continues. “There’s no sincerity with any of this electioneering this time. They are treating us like fools!"

This summer, Britton will be taking part in Channel 4's Time Crashers, a series in which 10 celebrities, including Greg Rutherford, Keith Allen and Kirstie Alley, are thrown into six different periods of British history, and have to try and live as though they're in that time.

She realises TV work may not be around forever, but Britton's adopting a healthy attitude to ageing.

"Instead of walking into age backwards, when you don't want to look because you'll see how you used to be, turn around and look into the distance of where you're going, and there's so much there to look forward to.

"I'm not ready for the scrapheap!"

A Good Catch by Fern Britton was published by HarperCollins on April 23, priced at £12.99.