The Opera singer, who topped the public vote in her semi-final last week, confessed she didn't think she would get past the first audition.
"I believe Collabro will win it," Lucy said. "I didn't think I'd get through the first audition.
"If I did win, I don't know what I'd do! I'd cry. I'd be in a mound on the floor."
Speaking ahead of tonight's show, Lucy Kay revealed her boyfriend has been "chuffed" by all of her male fans!
She explained: "I've had good feedback for how I look on Twitter. I've got quite a lot of male admirers! My boyfriend's chuffed. He can go 'It's my bird!'.
"We've been together two years. He's a runner and rigger for concerts - he's working with One Direction. I met him in a local pub and when I saw him, I thought, 'I love him'."
Lucy added: "We talk about marriage and babies all the time!"
The BGT 2014 final TONIGHT from 7PM on ITV from Saturday, June 7.
Browse pictures of the BGT 2014 finalists below...