I know what I'd do....
1) Sit down, make yourself a realistic study plan, and stick to it. It has to be realistic, or you'll fail to keep to it, and failure is not what you need.
2) Include the one hour flying a week in your plan. You will need one day off studying a week, or you'll go mad. Your brain needs that rest too. I'd make that day off your flying day. DON'T take A level work to the airfield with you; have a complete day off from study, and I guarantee you'll get more done than if you keep at it non-stop.
3) OK, 5 days a week at school. Make sure you actually study in study periods, and do a little when you get home. But make sure you take regular breaks, and eat and sleep enough. And go for walks or take regular exercise too. The exact details depend on you, but if you can't study for more than half an hour without your mind wandering, then don't. Build in breaks and food and so on, and use your time productively.
4) Make the day you have left a study day, unlss you need to do personal stuff or whatever. But no-one can study all day, so again, build in breaks for whatever you need. And make that the ONLY day you watch TV, go on PPRune, or do other timewasting stuff. (OK, five minutes a day on PPRuNe if you have to!)
5) In the summer, by all means cram for your A levels. But you'll still need breaks. Maybe an hour's flying a fortnight to not let your skills degrtade too much? But if that's not possible, you can easily get up to speed before the Skills Test by spending a few hours with an instructor.
7) A month to get your PPL ground exams in Nov/Dec is plenty.
8) Now, sit down, and make yourself a timetable. The reason it all looks like too much is because you're not planning it; you're going, "Omigod, there's all this stuff, I can't cope". Plan it, write it down, take the pressure off yourself. Once you do that, you'll calm down and be able to both study and fly more productively. Really! Trust me. It'll work.
