I can only echo the posts re: Bristol GS. Top school with quality instructors.
The first module I studied part time for about 6 to 8 weeks. Went to the brush up, worked like a bitch and sat the exams. For module 2 I studied in the states whilst instructing, realistically I didn't get too much study in, came home 3 weeks before the brush up course and studied hard for 3 weeks then went down to Bristol to finish off the ATPL's.
If you really would like to study full time at a school, I'd stay in the UK/Ireland. I've heard good things about the school in Bournemouth (sorry dont know the name or details) but I think heading to Naples to do full time ATPL's isn't an option I would of taken. Good luck what ever you choose