That's only the best thing to do if your UAI is safely within the acceptable limits (ie about 98.00 or higher).
As for the original question, the only way you can "transfer" to medicine (and this is already an extremely rare occassion) is if you're already in one medical course trying to move to another one. Otherwise you're just gaining admission, like any other applicant. Medical Schools tend not to give advanced standing for anything, often not even other medical study. No matter how "related" your field may seem, they'll make you do the whole course without exemptions.
Now, that doesn't seem to have answered anything at all.
Basically, there's nothing that you can do to permanently exclude the average joe from Medical study except giving up (and child protection legislation etc). You can just keep trying every year until they eventually accept you - so if you don't make it after year 12 you can go to uni, get good marks and apply again (as I'm attempting to do). It wouldn't be a bad idea to take the UMAT again, since you're bound to improve your score.
Oh, I just realised you may not have taken it at all. For all undergraduate medical schools except JCU you need to sit the UMAT in order to be considered for a place. If you did that but weren't offered a place, your UMAT is still valid the next year in case you want to apply again, so you don't have to sit it every year and fork out the pile of cash (just every second year).