I know how upset you must be feeling because I'm in the exact same position. But, for God's sake, be realistic, don't go suicide and be silly about this. For GCSEs I got 1A* 9A's 1B and for my AS I got:
B - Economics and biology (1 mark off an A)
B - maths and chemistry (10 marks off an A, I know it's a lot)
But, just get on with it now, stop contemplating SO much over things because the most you need to do is work work work. Do a few AS resits to bring them to A's and your main objective is to achieve those grades at the end of the year. I've learnt to accept the worst and the worst being is that we may get rejected this year and you'll have to reapply next year but as long as you've got your grades in the end, you're not in a bad position then.
I say go along with your UKCAT as normal, you never know your UKCAT score may suprise you (in a good way). Go with your application as normal, but if you get rejected, you get rejected, but definitely be focussd on getting those A's now. Don't waste your time on here thinking about those grades again and again, what's done now is done.
Most medical schools permit module resits within the two years, so just focus on getting your grades. Write a very strong PS and practice for UKCAT.
Be realistic now and just get on with it. If you do want to achieve those grades, your revision for your resits should start now. You have to have that work ethic from the beginning.
Also, try to convince your teachers to predict you 3 A's.
Also, it is possible, I know this guy on TSR who also got ABBB for his AS, did a few resits worked really hard and got A*AA for his A levels and got into medical school.