I agree you should stay in school. Make the most of it while it's still free! Get your PPL done over the summer holidays if you can and in the mean time try to get a part-time job to pay for it. Don't start ATPL groundschool until you have some idea how you are going to pay for your CPL and ME/IR. You only get three years from your last ATPL exam to get all of that done, and the ME/IR is not cheap! You also want an FI rating? From what I can tell becoming a flight instructor is a very expensive route to earning very little. I'm not trying to put you off, but you must realise you will need a decent paying job or financial help to even get that far. If you are relying on getting a decent paying job you may struggle with only GCSE's. Best of luck though!
