Interview: Girls Aloud's Sarah Harding talks ahead of appearance in Ghost - the musical

They toured, they split, they got back together then went their separate ways all over again after originally forming through the ITV talent show Popstars: The Rivals.

Some 20 consecutive Top10 singles and millions of pounds worth of philanthropic work later, the famous five are pursuing different careers. Harding is carving out a name as an actor, having appeared in Coronation Street for five episodes as Joni Preston, the wife Robert ditched to return to Tracy Barlow. She's also moved into musical theatre as Molly, in Ghost, alongside Andy Moss, best known as Sam in Hollyoaks.

Ghost the movie won two Oscars and starred the late Patrick Swayze, Demi Moore, Tony Goldwyn and Whoopi Goldberg. The film's most iconic and moving scene sat at the pottery wheel was famously performed to The Righteous Brother's Unchained Melody, which also features in the musical version.

Harding and Moss feature in a new production at Birmingham's New Alexandra Theatre, which runs from Monday until September 24, and she's thrilled.

"It's a bit of everything – excitement, nervousness, fear, elation, everything really," the 34-year-old said. "I didn't know if I had it in me to do a musical because when you're doing film or TV you can always do retakes, but you can't do that with a musical. But the one thing you do get is lots of rehearsal time, just like you would have if you were doing a concert tour.

"It's like a Girls Aloud tour, except instead of dancing I'm learning lines. I'm learning new songs but I don't have to learn 20 new dance routines, it's 20 pages – well, triple that – of dialogue. But your muscle memory takes over and it becomes second nature, just like it did when we were rehearsing our tours back in the day. There's a bit more to think about, with the staging and the drama and the emotion, and it's a very heartfelt and touching story.

"I took it on because I really connected with the story. I think everyone can relate on some scale to losing somebody they've loved. It really isn't hard for me to turn on the waterworks."

Musical theatre has always been an ambition. "I did a bit of training in acting when I was younger but singing was always my forte. I've done a few bits and bobs acting-wise, like St Trinian's, but this is my first proper lead.

"The singing is completely different too. It's not like you're belting out big hits and stuff, it has to come from inside. You have to internalise all that emotion and not be over-the-top with it. I have a whole new appreciation for musical theatre. I'm like the new girl in school."

Ghost tells the story of Sam and his beloved girlfriend Molly.

Walking back to their apartment late one night a tragic encounter sees Sam murdered. Molly is left alone, in despair and utterly lost. But with the help of a phony storefront psychic, Sam, trapped between this world and the next, tries to communicate with Molly in the hope of saving her from grave danger.

Harding has an interesting take on Molly. "She's a strong lady but she's vulnerable. She's lost the man she thought she was about to marry. She was deeply, devastatingly in love with Sam and he was taken from her so suddenly. They never had chance to say goodbye. There was no closure.

"Yes, I can relate to her. I've been heartbroken and it's really tough. And from Sam's point of view he probably feels the same because he doesn't feel it was his time to go. Things have to be resolved before he can finally say goodbye. The final scenes are so touching and I can't watch the film without crying. Anything with Patrick Swayze in, I love it. He was one of my heartthrobs growing up – him and the John Hughes films."

The chemistry between Harding and Moss, who plays Sam, is a stand-out feature.

"The first week of rehearsals was the toughest for me because most of the cast have done this before. They've trained or they've acted before full-time. They've had that experience I've never had before. I've been on stage and I've been a singer, but I've been a pop singer, not a musical theatre singer.

"But they have taken me under their wing. They'll go 'try it like this' and if I've over-sung something, like I would in the band maybe, they'll be 'hold back and save your voice for this part'. It's a different mic set-up as well. I'm not holding a mic, I'm acting."

Harding thinks the story means a lot to people because it looks at the issue of loss. "We're all born, we're all here, we all love, we all lose and we all have to pass on at some point. It's a fact of life and it's telling that story in a tragic but very loving and heart-felt way. It's about saying goodbye and mourning that loss. It's just so touching and I'm so honoured to be playing this part because the film was one of the most iconic films for me growing up."

She's delighted to be on the road.

"Oh man, I've missed touring, except I won't be able to go out on stage and go 'hey, Glasgow!" she laughs. "That won't be happening. It will be difficult not being able to interact with the audience because I'm so used to getting a crowd going. When it came to going out on stage I'd step up and get into my caricature mode of the leery Sarah everyone thought I was. People are finally going to see that there's a softer side to me they haven't seen before. Normally that side is reserved for behind closed doors, for my friends and my family.

"I don't like to show weakness. People don't, do they? People are going to see a whole different side of me and I'm hoping they'll empathise a little and go 'you know what, maybe she's not that bad a person after all'. My whole mission is to get the audience crying. I'm going to get this play sponsored by Kleenex!" she laughs again.

"I just like being on the road. I'm quite a free spirit and, like I say, I'm not always 100mph like everyone thinks I am. I live in the country so it's very chilled. When I'm on tour I love to take in new cities and I love to travel. When I toured with the girls I used to go out and explore places with some of the dancers, go for lunch, whatever. I like being on the move. I get bored doing the same thing.

"I really struggled with a structured job when I finished education. Don't get me wrong; I have a huge respect for people who do those jobs because a lot of them are very important. But I'm not that sort of person.

"Don't put Baby in a corner! Wrong film, I know, but I feel I'm a cross between Molly from Ghost and Baby from Dirty Dancing."

By Andy Richardson