Home Study A Levels

Hi,

I'm currently an undergraduate studying Literature. I plan to move into Poli Sci, which I intend to do a masters in, and hence think it would be a good idea to study Mathematics to give a grip of the statistical tools that will be invaluable in research.

I'm adequate at Maths; I got A's in GCSE maths and additional maths -- I just decided pursuing it at A Level because I was more drawn to the arts and humanities.

What courses would you recommend taking that will
1) Give me the knowledge I need
2) Be acceptable certificates/credentials when I make my masters application (or at least look decent on the CV)

Thanks
Richard