Hi, R T Jones,
I did exactly what London J did,
I started flying streight after I finished my GCSE's, flew in the weekends as I did my AS Levels. I also did the theory exams with the AS Levels, just like LondonJ, I didnt find it too difficult to cope as I enjoyed everything!
Got my PPL at 17. Now finished my A-Levels, 18 and doing ATPLs in the gap year.
If you have the will and determination, go for it.