Dr Anderson in Milton Keynes used to do very reasonably priced Class 2 medicals. I don't know if he's still on the list - worth checking out.
If you're serious about wanting to go on to Professional licence training, then its worth doing a Class 1 at the earliest opportunity. It is over £400 now, and you have to do the initial examination at Gatwick. It will be valid also for the Class 2 privileges and time periods. Renewal is then straightforward and much cheaper with a local AME.
If you only want a PPL, save your money and just do a Class 2 with a local AME.
Spend some time visiting the schools and asking questions at Cranfield, Sywell, Turweston......
Though be warned that Cranfield is often very busy and may lose you valuable training time due to traffic. Leicester isn't too far up the M1 and has a freindly, member-owned club.
I can also recommend a good chap at OSFC Enstone who does RT training and examinations - not sure if its members only.