Yeah, I wouldn't worry about whether the uni you apply to is top 3/5- they're all competitive!
It does however depend on the university- some of them rate A levels really highly, and that's pretty much the only thing they consider outside of personal statement/interview, but some of them (Nottingham especially) rate GCSE's really highly. The standard offer is going to be AAA-so if you think you can get that, go for it, but apply tactically if you think your predicted grades (A level) will be a disadvantage. Some universities weight applications highly on their scores in medical admissions tests (UKCAT, BMAT etc) so think about how likely you are to do well in those as well.
I wouldn't worry about AS predictions unless you think you're likely to get those grades- if you do really well in your AS's, the uni will see that. Good luck!