The 80s-set musical, based on the hit Adam Sandler film, runs at the Opera House until Saturday, with Lucie making a last minute replacement for ex-Emmerdale actress Roxanne Pallett for a six-week run though the summer as Holly.
She slotted into the show during its two-week run in Scotland, just a month after competing in the song contest, securing 15th place and the UK’s best result in years.
“It has been crazy,” the 2009 X Factor contestant said. “I’ve got so much going on too, I get married in August then I’m in Legally Blonde from September, as well as making decisions about what to do with my music career.
“I had pretty much no rehearsal time. The cast is very supportive and really helped me and let me do my thing - so long as I wasn’t putting anyone in harm’s way.
“But I’m feeling good about it now. I’ve definitely settled in - and I don’t need to look at my notes every two minutes any more like I did the first week.”
Lucie’s a seasoned stage performer, having appeared as Cosette in Les Miserables, Meat in We Will Rock You, Victoria in American Psycho and Maureen in Rent, as well as the lead role of Elle Woods in Legally Blonde.
She is joined by fellow X Factor singers 2006 finalist Ray Quinn and 2004’s Cassie Compton, as well as Hi-De-Hi star Ruth Madoc as Grandma Rosie and West End favourites Jon Robyns and Samuel Holmes.