You have 4A*s, 4A, 1B at GCSE and AAB at AS level and you call that mediocre. Lol.
Most uni's offer AAA for medicine. Which is what your predicted.
Providing you have two sciences, apply early, write a good personal statement, pass UKCAT and have a good interview - you will get an offer. Uni's value work experience, but it's not needed (you'd have to have good connections to get such work experience in medicine i.e. Be born with a silver spoon in your mouth). But that doesn't mean someone who has work experience in medicine will get an offer over you, or vice versa