are my a level grades good enough

are my grades good or average A*AB in Biology Chemistry and English literature in that order

are my grades good or average A*AB in Biology Chemistry and English literature in that order

Its the B…
Without contextual, most require AAA minimum, with A*AA or A*A*A
See
https://oxbridgemind.co.uk/ucas/which-medical-school-has-the-lowest-entry-requirements-for-medicine/#:~:text=Alternatively%2C%20universities%20such%20as%20Brunel,and%20the%20GCSE%20requirements%20too.

Have you done the UCAT yet? Or considering the BMAT?

yes i am applying to medicine and am doing the ucat will my B mean that I have to do really well in the UCAT

No
Predicted grades are used as entry requirement, although from https://www.ucas.com/advisers/managing-applications/predicted-grades-what-you-need-know-entry-year
‘Applicants do not always have to meet the entry requirements with their predicted grades to receive an offer – universities and colleges will assess applications on an individual basis. ’

I know that some, I emphasise I remember reading for a medical school, in their academic weighting, they gave points to your predicted grades.
But for example, Nottingham pre selection for interview scores your gcse’s, UCAT score and band. So check each medical schools selection process on their website before you apply

Although, ultimately, you will do this after your UCAT. What date is your UCAT?