Hi Ian_Wannabe,
Normally a flying school should be just like any other reputable business and refund the money that you have on account.
However there could be a side issue here whereby you paid them £2000 for 21 hours of flying at a slightly reduced rate. Ie, normally it is £100 an hour but they've included an extra hour as an incentive for you to pay up front.
In this case they have probably been charging your account at a slightly reduced rate so if you decide to ask for the remainder of the money back they will probably change the hourly rate to that of the normal hourly rate before returning what is then left (probably a little less than what you have now available if you were to use the rest of the money at the flying school).
Hope this makes sense!
Good luck with the Univesity course and the skills test for your PPL!
Best wishes,
Charlie Zulu.