I suggest holding onto the 2016 offer for Biomedical Sciences whilst reapplying strategically (links below). If you get an offer from a medical school, just ask your university to release you and go there. If not, well, then you have the option of doing Biomedical Sciences and going through graduate entry or trying again (although I don't know if you'd be up for that).
Here's the thing - funding for graduate entry is somewhat shaky and may be scrapped in the next few years so you might find yourself in the third year of your Biomedical Sciences degree realising that you can't actually afford graduate entry medicine. So you really should think of graduate entry as a last resort; the time, money and competition just aren't worth it unless every other option has been exhausted.
I also think it's somewhat naive to think that you can pay upfront for a medical degree, even if you do spend the intervening years working full-time. Most graduate entry courses are four years long (some are five years long e.g. Imperial), so that's £36 000 in tuition fees
at the current rate. George Osborne has announced in his budget that tuition fees are set to rise with inflation from 2017 onward so unless inflation is near-zero, the tuition will likely be more than £36 000.
Assuming that you are made an offer by a university that isn't local to you, you'll probably need to add to that figure the costs of rent, bills, food and other expenses over the four years. I don't want to scare you but the number is likely to be higher than £50 000, even on a tight budget. The NHS might fund the last year of your degree (the usual rule is that the NHS pays your tuition from fifth year onward but you wouldn't be doing a fifth year) but I'm not sure about that.
Here are some links on the resit policies of various medical schools and how to apply strategically (I understand you're limited in choice but even among those universities you can be a little bit more strategic):
http://www.thestudentroom.co.uk/wiki/Applying_to_Medical_School_using_your_Strengthshttp://www.thestudentroom.co.uk/wiki/Medical_School_Resit_PoliciesGood luck.