Ultimate High at Kemble has a good reputation, and ads in every magazine. But the truth is that your aeros course are only going to be as good as your instructor. So if you can find someone who loves to do and teach them, and find a suitable airplane, you can do them anywhere.
AOPA has an example syllabus which anybody can use, and there's also a suggested syllabus in David Robsons book.
As an introduction, there are "Loop Beginners Days" organized by the BAeA, which you can attend with no aerobatics experience up front. They take you up in a suitable aircraft, teach you the basics and then you fly a mini-competition based on the BAeA "known" Basic sequence. More information about this on the BAeA site,
Home page for the BAeA website.