sorry for ranting ........
You have to ask yourself if you actually want to do this degree or not. Most people feel a bit unsure of how well they did in their exams ( I know I am!), so at least wait until results day until you make any major decisions. Bristol is an excellent university and doing a degere in maths is going to put you in good stead for most careers - just make sure you're going because you want to and not for anyone else.