Basically i'm doing a BSc in Pharmaceutical Science and I'v been told that if I gain a first i should be able to apply straight away for a PhD...is this true?

yes, you can apply for a PhD with either a high 2i or a first.

From my experience, you are more likely to get a PhD with a 1st class degree but you can get on with a 2i (alot of my friends did).

Obviously it depends on where you obtained your BSc. I think Sir John Sulston got onto a PhD with a 2ii but that was from Cambridge.