I'm fairly certain the characters in the movie were from North Carolina, as were the characters from the original novel. I don't see why it would need to be changed. After all, I imagine British people would be less likely to notice the discrepancies in the actors' Southern accents.
I can't imagine this musical not doing well anywhere it chose to play; it's so beautiful and I believe pretty universal. I think any mature theater-goer would appreciate it.
"Wilkins, after all these years, are you trying to be funny?"