I fudged my a-levels and ended up with a B in mathematics. By some miracle I got into my insurance uni to do maths. I've thrived so much in the university environment and now I'm seriously looking to get the first I deserve. I would say that if you really enjoy it then yeah sure apply. Just be sure that you work hard during your degree to outweigh your A-levels on your cv at the end of it.
But if you really want a stronger understanding of maths before you go to uni, I'd suggest taking advantage of another year of free education and either re-sit some of your math modules or do further-maths. Seriously no-one will look down on you once you get to uni. So many people take a year out anyway to decide what they want to do, get the grades etc.