On the star-studded show being held this Sunday (February 10), she admitted: "I'm a bit nervous actually. I haven't even watched all the films yet - I've got three to go!
"I've watched so many - usually with a film I'll sit down at the end of an evening with a glass of wine but this time I've had to cram it all in."
Hosting alongside Dermot O'Leary, she said: "He's the voice of calm. I keep texting him saying how nervous I am and he keeps texting back saying, 'It's going to be fine!'"
Inquiring whether she'll be okay without her Xtra Factor co-host Olly Murs by her side, she joked: "I think I'll be alright without Olly - I think I'll survive. I've got Mr O'Leary. It's keeping it in the family anyway."
On rumours of Murs leaving, she said: "It's so early in the year to talk about X Factor stuff. We're both doing other things. We have no idea."
With Rylan Clark's name being thrown around to replace him, she said: "I heard that too. Rylan would be brilliant on telly. He's made for it really. I got to know him for six months - he's very infectious and lovely to be around."
Any romantic links with reality TV winner James Arthur she quashed and said: "I don't even know what they're about - we walked out of a club together. We went for a drink!"
She laughed: "We did walk down some stairs together and it was pretty erotic. I can't believe we did it. It was really hot!"
Talking about her BAFTA top films, she said: "I've got my favourites and I really love Les Mis. I loved the musical anyway and I loved the film more. I'm such an emotional person it made me cry so much.
"Anne Hathaway was the best thing I've ever seen. I really like Bradley Cooper's character in Silver Linings Playbook - you fall in love with him the more the film goes on.
"By the end you're like, 'Oh my god I love him'. He's hot, but I found him hotter in other films."
Having met a lot of famous faces, she still admits to feeling star-stuck. She said: "I probably will be by most of them, but then I do anyway when I meet people. There's going to be an incredible amount of talent on the red carpet.
"I keep telling myself, 'Be cool! Just be cool. Don't start fan girl-ing over Javier Bardem - that would be embarrassing'.
"I get star-struck by people I don't expect to be - someone like Brad Pitt, I won't be, then I'll be at This Morning and see one of the cooks and get star-struck! Like, they're actually a real person!"
On fashion for the big night, she said: "I really like what Jennifer Lawrence wore to the Golden Globes. I'm looking forward to seeing all the dresses.
"It's going to be freezing. I'm wearing long sleeves and long johns under my dress."
Talking about who would play her in a film of her life, she said: "No-one, buy maybe I'd get my twin to play me. Or the Olsen twins could play us - or the Sweet Valley High twins - or the twins from Fun House?"
When DS suggested Jedward, Flack replied: "In wigs. They've got quite feminine faces haven't they? They're probably prettier than me, actually!"
But she refused to comment on the One Direction saga of Zayn Malik allegedly cheating on Little Mix girlfriend Perrie Edwards. She said: "I'm not going to talk about that! That's no-one else's business."
Don't miss the excitement, glamour and E!'s complete coverage with Dermot and Caroline when Live from the Red Carpet: The 2013 EE British Academy Film Awards premieres on Sunday, February 10 from 5pm only on E! Entertainment Television.