Largely agree with what the people above have said although I think you would be better off resitting the B as you actually have a diagnosis for your depression, which should count as documentary evidence. With extenuating circumstances, most medical schools are willing to consider post-A2 resit applicants.
Have a look here for the resit policies of various medical schools:
http://www.thestudentroom.co.uk/wiki/Medical_School_Resit_Policies.
Some of them insist that you should have applied to them in the previous applicant cycle.
Also, if you have any contextual flags, Bristol does AAB offers for people from disadvantaged backgrounds, I think. I still think resitting is the best option though.
Good luck.