What degree are you wanting to go in for? As far as I'm aware many unis do extra maths (etc.) classes for people who may not have the maths skills required for the degree. Chemistry and Biology do, seeing as they typically do not ask for A-level Maths when making offers, anyway. Might be different for physics, economics, etc.
Are you learning it correctly? Obviously there's no strict correct way, but it may be that you're not being taught in a way which suits you. I find the best way to revise maths is to learn all the symbols and terms used in maths, what they mean and the context in which they're used as well as examples. What type/level of maths are you doing? It may help to use past-papers/practice-papers and mark schemes..