When you apply (I don't know if you know) but you will but in what you got at AS, then if you are resitting anything from AS during A-level you will have to put that you are resitting and what you are expected to get.
So, suppose you do get those grade but do need AAA, maybe if say you dropped Chemistry, and resat your maths module and was predicted an A, and you were predicted 3 As for your 3 A levels then it would be worth applying for your unis.
I think your personal statement may contribute if you convey a true passion towards your subjects but some unis are getting really picky on grades these days.
At my school everyone was told to have at least one back up plan as well, like a uni requiring ABB or something oppose to AAA (depending on your expected grades).