I hope this might provide some comfort, i honestly thought I like a month or so before my chemistry A level that like there wasn't a chance in hell that i would get an A and sort of resigned myself to the fact I'd probably get a B (if that!) to the point where I kept thinking how likely it would be that notts would let me in if i didn't meet their offer and like what i would say when I phoned up and begged them on results day to let me in etc.
But....it all turned out ok, i really hard during the revision weeks (like i'd go the library in town, big old pretty one, and stay there from 10-6 and work my socks off), and actually at one point a few days before my bio A2 i worried that i had neglected it due to concentrating too much on chem. On results day it turned out that I did meet the offer plus more, and didn't even just scrape the grade in any of them (this isn't just some show off story lol, i'm just proving that it can be done even if you don't expect it, which I didn't)