your a levels are so good, i honestly would say a second gap year is better than grad entry! especially bc a levels aren't valued at grad entry and that is really strong for you. there is no guarantee you could come out of biomedical science with a first/2:1 and that is also another 3 years of studying and waiting to apply. you mentioned understanding where you went wrong for interviews, so i think you'd be ready to reapply next year and potentially get your offers. not only that, but the funding for a med degree after a first degree gets really difficult, and as you mentioned the competition is crazy, i applied for grad entry this year (i'm in final year biomed) and almost everyone i spoke to that also applied was older with a lot more experience than me, either academic or life or work experience. but that isn't to say it's impossible, ive got 1 offer so far! so i think really weigh up your options and try to not see biomed at cardiff as a waiting period to apply to med again because it will be difficult and full on because it is a degree itself still!