I’ve taken Maths at AS Level. As other members have mentioned the step up is quite a big one but it doesn’t really seem huge to me because a lot of it’s about just coming to terms with new (not so difficult) methods as well as common sense. If you enjoy Maths and feel at ease with algebra etc. I really recommend it because the subject is fast-moving and a lot of the topics/questions you come across are really similar once you get to grips with the basics.