If you're at GCSE level then you haven't got long to go until you can make some of your own choices. Bite the bit and get on with your course work, focusing on getting good grades. If you try to think ahead of your present situation you're a good way along the way to solving your problems.
Perhaps you can consider moving to take AS and A levels? There are many very good schools and colleges and perhaps a move would benefit you. I know of many students who have moved between GCSE and AS/A level and have benefited well from the move. I understand what it's like to be unhappy at school but there are ways around this. If you can talk to your parents or another adult who will understand perhaps you can compromise on another route to your further education?
Try very hard to see this phase through with the hope of better things to come very soon. It's worth it when you are rewarded with the results that let you move on in your future. Good luck
Okay, fair enough, school is not for everyone, I didn't enjoy it one bit either. If you are truly committed to doing well in your GCSEs but having trouble at school, there are a number of ways you can improve, but it requires commitment and hard work. Still interested?
Okay, think about getting a personal tutor. Can't afford one? Yes you can. They don't charge that much and you will have a much better learning experience. Someone who has just graduated University will be cheaper than a teacher but won't be as familiar with the curriculum. But you can't afford one? Yes, you can, get a job doing a paper round or in a local shop and you can easily afford one, not only that and you will show initiative and your parents will be impressed.
Secondly, you can purchase or borrow from a local libraries, text books on the subjects that you want to do well in. It would be difficult for something like art, but perhaps there's an art club you can join.
Lastly, try the BBC's website Bitesize and they also have programmes on late at night to help with exam revision which will really really help. If you have a video recorder, you can view these programmes after school is over.
Once you put some of these ideas into action, school will seem simpler, you will accelerate and people will notice!