I can only vouch for Ravenair as i done my PPL there. All the instructors were great. I also stayed mostly with the one instructor. That way they know what you need more help with on the start of each lesson so you don't have to have different instructors each lesson finding out your weekneses are on your £££'s.
On airfields, I have also trained at Blackpool which is great but i consider Liverpool the better of the two as it is a lot busier, so in my opinion better to train in that environment as it is a great confidence booster for when you go further afield. You may well have to throw in a few orbits for the big jets but it's all great confidence building.