(cont) Your current school might be able to help, though it would probably be a better enviroment to study at a college.... you find a larger percentage of students there attend because they want to learn, and the attitude tends to be more mature..... A long shot would be home study/tutoring, and there may well be help available with that from your local education authority.
All in all I don't think the situation is as negative as some are making out, from what I'm guessing of your situation there will be someone willing to offer you the help, and you may well find the change will be of benefit to you. The idea of an extra years study never appeals, but it doesn't carry the stigma that you feel, many a person drops out and starts again at GCSE, A level, Diploma etc. Now your out of compulsary education (i think, or has it now changed to 18.....) the attitude is far different.