If the instructor has asked you to book 4 hours as an intro with groundschool, there is a slim chance he may want to charge you for 1-2 hours of groundschool. Most schools would not charge for this, but having said that ex1 & 2 of the PPL are both ground exercises so I see no reason why they should not charge for them, your first flight was ex3 and you were happy enough to pay for that.
The normal way a school works is you pay for the flying time, which is taken from when you took the brakes off to when you set them again after the flight. So for a typical flight you would book a 2 hour slot, initially go in the classroom with the instructor for 15-20 mins for a brief on what you are about to cover in flight, then go out to the aircraft and spend 10 mins checking it and doing paperwork, fly for an hour, then 30 mins of debrief and paperwork.
In this two hour slot you would only pay for the time flown, whatever it is. I say 1 hours as this is typical, but if you only flew for 45 or 50, that's all you pay, same as if you fly for 1:20 that's what you pay.
As this is your first proper lesson, it is a bit of an exception with the additional groundschool, so your school may or may not charge, but all other pre-flight briefs should be included.
Any additional groundschool you request, for example if you specifically wanted some tuition on Air Law in your own time, I would expect this to be charged at £20-£25 per hour, after all the instructor has to make a living, and the school has to pay the electricity bill.
To be clear, the 45 hour minimum is flight time, not groundschool or any other tuition. Be aware that this is a very tight minimum, and a far more realistic figure is 55-60 hours.
Last edited by RTN11; 19th Mar 2013 at 20:58.