Go for it. I found most of the exams reasonably interesting (with the exception of Air Law
) so I reckon it's a good way to get started.
Only thing to watch is the timing of when you do the exams. All seven must be passed within an 18 month period, after which they remain valid for 24 months from the date of the final pass. As you're 14 1/2 you shouldn't start too early - if you finished them all tomorrow then the passes would expire before you could apply for a licence - but that's not really much of a problem. All the regulations are in Section C of
LASORS.
Enjoy!