Sounds like you're prepared to work hard, then I'll say go for it. year 1 contents aren't too hard as long as you have a good base knowledge, and if you understand mechanisms (as in movements of electron pairs, curly arrows) for organic reactions then the rest of organic is all right.
As for physical, they extend on your GCSEs atom knowledge, ions and equilibrium, rates, titrations, bondings, redox etc and aren't as hard when you get used to them. AS chemistry is okay, the real toughest barrier is to not see all the content and panic (like so many people who drop it the first week), they'll eventually make sense. And of course A Level Year 2 is where the toughie really are in, AS in comparison is almost easy