You really need to do some research into Medical schools which don't take into account your GCSE's as much as others when scoring applicants. For example, it'd be useless applying to universities that want X number of A*'s at GCSE as a minimum requirement. Comb over the minimum requirments for Medicine at various universities online and look for those for which you'll have a chance.
I'd also note with those GCSE's try your best to perform well at the UKCAT then apply to universities which use the UKCAT to rank applicants when offering interviews (e.g. Newcastle I think) and then try to wow them at interview.
I'm not sure but I think some of the universities that your GCSE's might not be too much of an issue when applying (if you score highly in the other areas) are: Barts, Aberdeen, Birghton and Sussex, Dundee, Durham, Kings, Leeds, Leiceter, Newcastle, Peninsula, Southampton and St Andrews.
However although the ones above don't score specifically on GCSE's or ask for a set number of GCSE's officially on their requirements by no means is to say that they don't consider them when selecting for interviews. Personally I'd say your best bet is to aim for the Unis which really focus highly on the UKCAT in their selection process and aim to ace that.
Good luck, it's still definitally possible for you to get into Medical School but make sure you can balance out your average (only in a medicial school applicant context!) grades with strong critera elsewhere.