Hi,
Why does it need a new water-pump at that age? Is it leaking at all, or making unpleasant noises? If not, you may find that you're being 'had'.
Apart from that, the belt would probably cost about a tenner, and take a determined, skilled mechanic about 2-3 hours to replace if he was properly familar with the model and hit no snags (on a 2001 model, I'd be amazed if there were any difficulties at all, but you never know). On that basis, I'd have said that £300 would be a nice little earner for someone ... I'd be happy to do timing-belt changes all day, all year for that sort of money.
Good luck
Philip