Not to be a thorn in the bush to all of you because I somewhat feel you guys after getting rejected post interview at QMUL, however I'm in year 13. But what I've noticed so far is that A-levels are not a determining factor, yes they're grades you need to achieve to actually confirm your place, but the fundamental to getting an offer; UCAT. Most effort needs to be put into it, as a high UCAT will guarantee a lot of interviewees, if also applied strategically. Again my UCAT wasn't that high, but I applied strategically and did quite a lot of research with my friend, doing FOI and looking at past data, and landed 5 interviews (5th being medicine which converted into an offer). But I think the crux of the matter is to focus all your attention on your UCAT, as regardless of what universities say, I believe they will always have the UCAT in highest regard and importance.
So it's not so much that they brush off your efforts and A-levels but the thing is everyone puts a lot of effort into those so they need more to 'differentiate', not to say that a low UCAT means you won't make a good dentist or whatnot.