Some places do now ask for MCAT scores from US applicants.
Max bank loan is £25K from HSBC but as you aren't British you couldn't get it anyway, or probably any other loan in this country. I expect you could still get one at home though?
As for tuition, UK grads on our 4yr courses only pay 1 yr tuition, no idea if this would be the same for international students but you should obviously check.
Your best bet is to look at websites. Places with 4 yr courses are- Kings, Barts, St Georges, Imperial, Nottingham, Liverpool, Birmingham, Oxford, Newcastle, Bristol, Cambridge, Keele, Leicester, Warwick, Southampton and Swansea. Most will require UKCAT, some require GAMSAT which is a lot harder but not that bad.