My daughter started learning to fly when she had just turned 15, so you might like to consider these points...
Try it asap, to make sure that you really do enjoy it. If you do enjoy it, do you want it to be your hobby or your profession. In 6 years time you may have changed your mind, so make sure you don't take any decisions that preclude you doing something else. Check you aren't medically prevented from becoming a commercial pilot (e.g colour blindness etc etc etc)
There are many scholarships available, see the links on
Junior Gliding
Gliding outside the Air Cadets is extremely affordable for a youngster (my club is £40/year plus £6 per launch). Find your nearest club at
British Gliding Association - UK Map
Understand the cost vs time tradeoffs for Air Cadets and club flying. When learning it is advisable to fly as often as possible - I made little progress when only flying once a month.
My daughter was flying aerobatics in gliders -- loops and spins at 1500ft -- (with an instructor behind her of course) when she was 15, and she wasn't the only under-16 doing it. You could too. The major danger would be that you might get bored flying straight and level in powered aircraft
