Oh I also did maths, it is massively time consuming. Unless you are really good be prepared for grades like Us and Es in mocks (hopefully not in the real thing but it can happen). You have to work and revise on it so so much.
(Personally, I got a C at AS and then dropped it because I realised I'd never use it in real life and I'd only taken it because I was told how prestigious it is - btw, I have just finished uni and to this day, that AS maths has not impacted my life, having a GCSE was enough. Although I guess the extra UCAS points are good.)