I got 8A* and 3As at GCSE and AAAABa at A-Level, with a Top 5 in Geography.
To be honest this is a bad place to seek reassurance as TSR is, as far as grades go, not a fair representation of the population. If you meet minimum GCSE requirements for universities (checks prospectuses and UCAS) and are capable of getting AAB as a minimum at A-Level including Chemistry and most likely Biology as well then you have a good a chance as anyone providing you have the necessary work experience and a good PS.