Hi
Doing your PPL abroad is a good idea and you should have a great time doing it.
No need to get a JAA PPL, all you need is an ICAO PPL to start the ATPL ground school (FAA would be fine).
Doesnt make any difference where you do your training, BCFT do tell people that the airlines want you to do all the training at one school, this is just sales talk. FlyBE is the only airline that has said they want modular students to complete their CPL / ME IR at one school, they dont care where you do your PPL, ground school, MCC.
Other airlines dont care where or how you do your training, except BA who only take cadets from intergrated schools.
There are some great threads on here, have a read of them. Best place to get information is from the people working in the airlines, the worst place to get information are flight schools! they only want your cash and will tell you what you want to hear.
Good luck with your training, and I hope things pick up when you qualify.