Story of a successful resitter (with some extenuating circumstances), for those interested. I know when I was in this situation I really wanted to what had happened to other sand get advice etc, so hope this is helpful.
In the summer of 2012 on results day I got back my A level results of ABBC, (maths, biology, physics and chemistry). I therefore missed my offer of AAAC at King's College London. Obviously there are a few days/weeks of despair, dilemmas and uncertainty, but in the end I decided that I wanted to reapply to medicine, not take a clearing course, go abroad or do grad med (which are all options and you should give then consideration).
Now, I had some circumstances at the time, which I hadn't declared to my school (parent suffering depression, difficult family situation - nothing that dramatic but anything that may have affected you at all is worth mentioning, could open up more med schools for you and make tutors looks upon your application more favourably.)
So I, along with my parents (if your parents are supportive if strongly advise you to take them when talking to teachers, schools tend to be more receptive/helpful and more likely to take you seriously if you come with parents) went to my head of year to bring these up. They obviously said that we should have mentioned them earlier, but agreed to mention them in the reference and write me a supporting letter to send to unis.
Now here's the important bit for any anyone with any extenuating circumstances - I then emailed every single medical school to ask whether they'd consider me. I created a list of my results, listing my GCSE's, my AS results, all the good A level modules etc I had achieved, my UKCAT score etc - pretty much anything that made me look good. I also attached the letter from my school explaining my circumstances. I wrote an email about how keen I was to study there, outlined my circumstances and sent it to every medical school. I had varying responses. A couple, such as UEA, Exeter said that they'd consider every resit applicant anyway - that info is likely available on their websites so you need to look into that. Some, like Manchester, consider resitter with ABB and above. Some, such as a Queens university Belfast said that they would have considered me if I'd applied to them lady year (so make sure you mention in your email if you did apply last year). Some gave me a straight no. Some, such as Aberdeen and St George's said they'd look at my circumstances after I applied only.
HOWEVER, a couple, said that they had looked I went information and would consider me personally based on what I'd submitted. These were Leeds and Sheffield (I think there were a few more but I remember those two as I applied). Anyway, I'd strongly advise you to do this. My documents were attached to my application so it would be considered alongside those and obviously I got extra universities to apply to, giving me some choice to apply to those with more favourable selection criteria for me.
Anyway, I'm now at Leeds, having just completed first year
once you apply, don't obsess over your application, focus on the work for your A levels and make sure you absolutely nail it. Come up with something productive to do in your gap year. Write about your reaffirmed commitment to Medicine on your PS.
Feel free to message me if you have any more questions, hope I was helpful!