It helps a lot to be intuitive, but I've found that you can get a very long way in a maths degree just by standard practice and content. (I'm a fourth year maths student). I can't say for sure, but I think you could probably safely get a 2:1 if you work hard.
Haave you done anything like the UKMT maths challenges, AEA or STEP? They aren't necessary, but they are a different kind of maths (don't worry if you look at a paper and find it hard - there are a lot of techniques people doing those papers will have learned outside A-level).
Edit: *2:1!!! If you saw that before I changed it, it was a typo.