Well, if you're on 6 A*s, 3 As and 3 Bs already and you're only in Year 10, I'd say you stand a pretty good chance in terms of grades, but like the above poster, I don't know anything about the school either, so that's just a guess really. The only thing I would say is that you'll most likely need to be predicted A*s in the subjects you want to do at A-level, so you'll need to work on the French.