Your A level grades will be the most important. But note that the US admissions system is not setup to interpret “predicted” scores. So they’ll focus more heavily on your GCSE. And the “C” will stand out.
Since the A level results aren’t released until August, this puts more emphasis on your SAT score and GCSE. Admissions readers at the big colleges will understand your situation and take it into account.
Overall I think you’re in the ballpark, but a lot of other factors come into play: financial aid, URM status, etc. Far from a slam dunk.