Crikey Sam, you have just started school, don't worry about what to do after leaving it! Enjoy life whilst you can. If you want to enter the ents industry...and you are not certifiably insane...then read ALL the posts in BR which touch even briefly on the subject.
You will read that your question has been asked almost too many times to count, even for the relatively short time I have read BR.
If it's tech stuff you want to do then do tech subjects at A level, none of this namby pamby nonsense with media studies or advanced macrame and similar. Maths and Physics for a start and think about English Lang' too. IF you then decide you don't want to follow the technical theatre career path, and it is entirely possible, at least you have a very respectable set of As.
And don't come out with any more nonsense about having done professional stuff either, or having done "loads of shows", lol. (Hmm, English Lang' might be very useful.) You have not done pro stuff because you are too young, and, you should not be doing "loads of shows" because you are supposed to be at school studying for some "fairly" important exams in about two years, followed by even more important exams in two years after that...
Don't even think about stating, as one young lad did only a few weeks ago, that you have run crews for example, because nobody will take you seriously. Running a crew and simply being "promoted to stage monitor" by your teacher are two different things entirely. If, in modern parlance, you big yourself up, you run the risk of being questioned on some ludicrous claim. When you receive your letter of rejection you can bask in the warm glow that you, yourself, managed to talk your way OUT of the job.
In addition, and we say this to all the posters such as yourselves (not just you)...your future employer is very possibly reading this forum...and it might be that (s)he will have a look at your posts before binning (hopefully not) your letter of application.
(You might as well learn today, here and now, that very recently at a place where I do the volunteer thing a manager binned over a hundred job applications out of one hundred and twenty odd. This manager is no soft touch and she has the enviable skill of reading "behind" the nonsense on the forms.)
Internet posting includes bragging about dumb stuff on Facebook too...odd as it may seem to you now but there is no upper age limit for having a Facebook account...and it is amazing what folk post...
Oh and watch out for asking too many homework questions if you go the college route...and think twice about asking folk to complete a questionnaire which asks fatuous questions; the answers of which will tend to be even more fatuous.
Bottom line Sam is you really are far too young to be worrying about what you are going to do when you leave school. Technical theatre for you is, at this moment, an all consuming hobby and it is very easy to believe that this hobby will evolve into a career. This can happen of course but for the moment enjoy it as a hobby. In a year or so you really should start to get your head down into some serious school work..just reread the quote in #11 above, then reflect.