For info: some sample questions, and other pre-reg info, can be found here:
Rpsgb.org: Examination
There's a book called 'Sample Calculations' (I think) published by the Pharmaceutical Press (it has a yellow cover) which is very useful and well worth buying before starting pre-reg.
BUT...since you're only in your first year don't waste time worrying about whether of not you can answer the questions. Everything will fall into place in due course (mostly during the pre-reg year!). Until then, relax and try not to worry too much about your marks/competance at pharmacy.