Studying Statistics at degree level at Warwick?

Hi, I'm in love with Warwick the uni. But I recently got an offer to study maths and stats there! the only problem is I am not sure whether I like stats enough to do it there? I certainly love maths enough. The Mathstats course there is very statistical based, and I dont think it is then possible to go on and do a P.hD in Pure Mathematics, (Which I would like to have the option to do) ?

Current Students at Warwick, doing/(know anyone who is) do Maths and Stats at Warwick, how easy is it at the end of your first year to change?

Also what advise would you give me?

(I'm soon self teaching myself S3)