Buy a cheap PFA single seater such as a VP1, group-A Minimax or MW7, which should cost you under £4k if you shop about.
Spend a happy summer touring the farmstrips of Britain, doing your own maintenance and running on mogas - should cost around £20/hr
Sell it for probably £500 or so less than you bought it.
Total expenditure about £2500 for 100 hours flying.
Pay off the money you borrowed to start with, less the £2500 or so that the flying has really cost you.
G