It depends on what subjects you are doing. Also like the above person said, you can pick your subjects this time, and there will be a couple or no compulsory subjects depending on your college, unlike GCSEs where most of your subjects are compulsory. You can also drop subject(s) after AS level, but at the end of A2, you should have done 3 A-levels.
Its a big step from GCSEs, you may need to revise better, do more modules, more homework etc.