Coke 611
I started my PPL when I was 15, and my advice, if you want your savings to go further, is to wait until you're 16 to 16 1/2, and to get a class 3 medical before you do any more flying than a trial lesson. I hung about for ages not able to progress until I was 17 (the youngest you can go solo) and consequently spent ££££s on excess hours.
The reason for the medical so early on, is the simple fact that if you fail it, you won't have blown close to £1000 on wasted flying.
I got my ppl, went to uni, did a couple of 'normal' jobs after uni, then got into NATS 1st time (Luck rather than judgement I think)
3 yrs after joining, I'm out of the college, and valid.
I'd recommend at least going to Uni before joining, just in case you need something to fall back on.
I think if I'd joined straight from school I would have found the training even harder, and may not have succeeded. (But that's just me)
Remember, you want to be an ATCO, not a pilot, and if you fail, you'll try again next year!
Hope this helps
Cudds