Ashleigh & Pudsey will take to the stage again tonight (May 6) for the first live semi-final, and Butler revealed she is "very nervous".
"I am very nervous about performing on the live shows," she said. "I feel that because everyone loved our audition routine so much, we have to make our second performance even better, which puts a lot of pressure on Pudsey and I. We don't want to let anyone down, especially Simon!"
The pair wowed the judges during their audition, with Simon Cowell declaring them "the best dancing dog act" he had ever seen.
On what she would do with the £500,000 prize money if they won, she revealed: "If we did win the £500,000 Pudsey would be getting a new bed and a posh collar, and he'd get the very best treats - steak probably! Also a big dream is to set up my own business training animals for film and TV.
"I feel Pudsey would be perfect for film work because as soon as someone reaches for their camera he is there waiting and posing!"
When asked why they should win the talent show, she added: "I think Pudsey and I should win Britain's Got Talent as over the years there have been a variety of winners... singers, dancers, gymnasts. I feel it's about time a dog act won! We have worked so hard for this and we have made sure we are enjoying it every step of the way!
"I can't describe how I would feel if Pudsey and I won. Pudsey means everything to me and I know that all he ever wants to do is please me. It would mean all that more because I would have won alongside my best friend!"
Butler recently told Digital Spy that she feared letting down canine acts around the country before she auditioned with Pudsey.
The semi-finals begin this evening at 8pm on ITV1 (May 6) with a two-hour special. Episodes then air daily until Thursday (May 10).
Each semi-final will include nine acts performing live for judges Simon Cowell, Alesha Dixon, Amanda Holden and David Walliams.