Hiya! I've been looking into pharmacology myself too! I do know Aberdeen looks for very low grades - the prospectus is upstairs so can't be bothered to check the grades right now, but it specifies for C's and D's and if you want entry into the second year then you need B's and C's. Of course being Scotland it's a four year course. But Aberdeen is pretty good.
After pharmacology you can't practise as a pharmacist yet - you gotta train and past loads of exams - a nurse, whose daughter is training as a pharmacist, once told me that her daughter has been studying for something like 7 years and still gotta pass some more exams before she is fully qualified. It's a long route, pharmacology.
Btw are you sure you can handle the chemistry and biochemistry in pharmacology if you got a boarderline C for chem? I don't mean this horribly, but I got a C for chem too at AS, a mark off a B and there're the most basic of stuff that I don't get or can't do because my chem basis was so poor. I was trying to figure out if breaking of bonds gave out or taken in energy
that's how bad I am! And I'm only on about A2 at the moment - wouldn't you struggle in pharmacology, at degree level, with a low C at AS? That is presuming you worked hard during AS. If it was just a strike of bad luck during the exams then you should be fine.
Sorry that seems so harsh, but to be honest the uni's might be thinking a similar thing. But if you think you can handle it and a low C isn't your maximum capability, then go for it. Good luck!