Hi
It sounds like you have come through a lot, so well done for sticking with your dream! I am 24 and just finishing an access to medicine course at the moment. What I would stress is access courses or a levels are only as successful for medicine entry as the applicant. If you are the right applicant it is possible to get in with either. I first trained as a nurse and completely agree with your opinion on the lack of science, which is what made me change to medicine. If you are over 21 most universities expect you to apply through access (not that a levels are discouraged, its just more normal for a mature student to do access). I received 4 interview offers and so far one conditional offer to study medicine at Glasgow (which i'm likely to firm as it's my favourite, I love Scotland! I am English, not Scottish). Many universities accept access to medicine and it is only a one year course, where every unit is tailored to a medical degree, whereas a levels incorporate all areas of a subject, not just the medically relevant. Also being on an access course means your reference will be from a reliable tutor who knows your studying capability at present, this can make a big difference on whether unis think you will attain the correct grades.
My advice is prepare very very hard for the UKCAT to get a good score
Write a great personal statement and get as many people to check it over as possible.
Pick the correct universities... you only get 4 options, choose wisely