bsw,
Cant really speak for larger schools as I am relatively inexperienced. I recently did my PPL with one of the schools you mentioned in Exeter, and imho Exeter provides a good balance.
Its not too busy on a normal day for you to get a radio call in, but not so silent you think your radios bust! You get enough commercial and GA traffic to keep you on your toes, particularly in the circuit on a busy day. Only problem I had with Exeter is fuel is f*cking expensive and as the runway is so long it took me a while to really get the hang of short field as I became used to 2km of runway outsretched in front of me!
Your instructors will take you through and hurl you into controlled airspace, tiny grass strips, no man's land and elsewhere, so no worries on missing out on any experience in training. To my knowledge you cant do ATPL in Exeter, have to go to Bristol or Coventry (I think, correct me if I'm wrong somebody!).
There are pros and cons to doing a modular, likewise for an intergrated as you will see if you browse these forums. Whatever you do, you will thoroughly enjoy every minute you spend flying. The two years I spent at my flight school were the best of my (so far short) life, and I wish you the same enjoyment and best of luck in you career.
h