I just finished my second year studying maths, and over the holidays after finishing year 13, I also started worrying that I wouldn't be able to cope with the differences between maths at school and university. Everyone seemed to stress how uni maths is more about understanding rather than learning the format of the exams.
Whilst I haven't really enjoyed my time at uni, it's not because the content is too hard, or exams are a really weird format. I'd say revising for uni exams is pretty much the same as revising for school, so fears in that regard are unfounded.
Good luck, and I hope if you choose to go, you have a really good time!