Daniel Ainsleigh's reply:
If acting is truly what you want to do then, I’d strongly advise you to train on a course that is accredited by the National Council of Drama Training (NCDT). A list of accredited courses is available on their website. Almost all of these courses are open only to applicants over 18 years of age. It is important to these schools that the applicant is fully committed to acting as a career choice, so it’s handy that you’ve included drama in your school options.
Membership of any drama clubs or youth theatre groups at school or in your area is also very useful. I think doing drama at GCSE and A Level is great and it’s not important to specialise in only-drama training now. Indeed, many drama schools actually prefer their applicants to have a rounded education. Also, most of the NCDT courses are now BA degree courses and A-levels are a good stepping stone to degree level.
My advice to you would be to continue with your schooling at A-Level, including Theatre Studies if your school offers it, and to get involved in any school or local youth theatre groups.