The Great Celebrity Bake Off is back - and the heat is on to raise more life-saving dough for Stand Up To Cancer.

Now in its fifth year, the charity spin-off series makes a welcome return to Channel 4, complete with a fresh batch of 19 celebrities, each vying for the coveted Star Baker apron.

But they're not the only famous faces hoping to impress Prue Leith and Paul Hollywood, for this season longtime host Matt Lucas also finds himself in the firing line of the judges - and his fellow presenter Noel Fielding - as he fills in for a missing baker.

"(It's) terrifying!" quips the Little Britain star, 48, who is used to presiding over the bakers' efforts. "I only found out just before. No time to prepare. Mind you, no time to worry, either!"

Can he bake? "Wait and see!" he teases. "My strengths generally are saying no when people ask me to compete in baking shows - one that failed me on this occasion!"

So just who will be joining him?

THE ALL-STAR LINE UP

As usual, stars from the worlds of music, entertainment and sport haven't shied away from rolling their sleeves up for this great cause.

Doing their bit for Stand Up To Cancer are: comedian and creator of Taskmaster Alex Horne; international broadcaster Annie Macmanus (better known as Annie Mac); actor and children's author Ben Miller; actor Blake Harrison; broadcaster Clara Amfo; award-winning comedian and podcaster Ed Gamble; singer-songwriter and UN environment ambassador Ellie Goulding; TV presenter Emma Willis; and singer-songwriter Example.

Fans can also expect to see choirmaster and broadcaster Gareth Malone; actress Katherine Kelly; TV presenter Laura Whitmore; actor, writer and comedian Mawaan Rizwan; Olympic gold medallist Sir Mo Farah; judge, presenter and dancer Motsi Mabuse; comedian, writer and TV presenter Ruby Wax; TV presenter Sophie Morgan; actress Tracy-Ann Oberman; and comedian and musician Yung Filly.

THE PROCESS

Sliced up into five episodes, the latest series will follow in the footsteps of its predecessor, inviting four brave celebrities into the iconic white tent every week.

In a bid to win, they will each compete in three rounds: the Signature, the Technical and the Showstopper challenges. It is then up to Hollywood and Leith to judge their culinary creations, before just one hopeful is awarded the sought-after title of Star Baker.

But who fancies their chances?

"I can bake a little bit!" declares Goulding, 35. "I wouldn't say I'm fully confident as a baker, I often get bakes wrong. I tend to move away from the recipe quite a lot, which proves to be disastrous."

"I cannot bake. I have never baked. My children can bake better than me," Horne, 43, compares. "But I saw this as an opportunity to learn a new craft and possibly fashion a new career. I'm only doing it so I can release a cookbook. That is not true. I can't bake."

"This is the first time. But you know what? I'm really enjoying it!" admits Farah, 38. "I can see myself doing more."

"I would say I'm OK with my baking. I enjoy baking, it's almost like meditation. I like putting everything together and getting this beautiful result at the end. Usually!" says Mabuse, 40.

As for Example, 39, "I don't like baking at all, it's too specific when it comes to measurements. Which I hate because I hate rules! But if I HAD to bake for a competition then I would do everything I could to win it!"

THE BAKES

Ask Goulding to make a chocolate fondant and she could be in trouble, she warns: "Something that requires a lot of timing and is really technical (would be a disaster). So a fondant cake or a puff pastry or something!"

For Whitmore, 36, it's Baked Alaska: "I once tried to make (it), and I basically made a baked omelette. I actually didn't even think about what they might ask us to make, but I really hope it's not (that)!

"My favourite cake is a red velvet cake, that's my favourite thing to do," she adds. "And as a kid I did love my mum's apple pie, because our neighbour had an apple tree in her garden, so I can make that. Just stick with the basics and what you know - chocolate cake and apple pie."

If its simplicity you're after, "I kind of dabble with my kids and make cupcakes!" Willis, 45, offers. "I can do a sponge, but that's my limit. A big sponge, whack a bit of cream and jam in it, put some icing sugar on the top to make it look pretty, but that's the extent of my baking skills!"

THE GOOD CAUSE

In standing up to the challenges, and to cancer, the celebrity bakers hope to inspire viewers to do the same.

"I much prefer to appear on screen as a character. However, I made this exception as Stand Up To Cancer raises money for cancer research and treatment and my entire fee is paid directly into that fund," reasons Kelly, 42. "It's a terrifying disease. Anything that can be done must be done."

"So many people I know, that's what they die of. So I'm doing this for them. And for everybody else," says Wax, 68.

"One in two people will get cancer in their lifetime, so if you haven't been affected by cancer, the chances are someone in your life has," Harrison, 36, realises. "So I think everyone's just trying to do their bit, really. It's so important to raise awareness and to help raise money for research."

Amfo, 37, agrees: "In the past few years, four lovely women that I know, of my age, have been diagnosed with cancer, and it really hit home to me how universal and cruel cancer is. It doesn't discriminate between class, or gender, or race, or sexuality, it can happen to anyone.

"It's not just the person with the illness, it affects everyone around them that loves them," she finishes. "That's why Stand Up To Cancer is so important - we need to fund research that could be life-saving."

The Great Celebrity Bake Off for Stand Up To Cancer, Channel 4, Tuesday, 8pm.