Hey there!
I thought I'd pop a quick message to give some insight:
1) Have you looked at the Biomed course at St. Andrews? Once you finish it you can transfer into year 3 of the Manchester Uni Med course, not sure how competitive it is but I know they take quite a few students from St. Andrews. Plus you'd only have to do 2 years and then you'd be ready to go into Foundation training!
2) If you really think you want to do medicine, then take all the time in the world i.e. take another gap year. It may be difficult because it seems like all your friends are at Uni moving on with their lives but the last thing you want to do is a degree you don't really want to do (it's a tad soul destroying.....)
3) If you do decide to do a degree in Biomed before medicine, then remember that your funding changes i.e. you get zero from student finance once you start medicine (unless you do a very competitive GEM course). So again, if you really really want to do Medicine then wait another year and improve your application to a point were they can't refuse you.
Hope that helps!