That's a good tip Rhiannon - the carpark you mention is the one behind Waitrose isn't it.

Parking in the High Street is not easy, but another little known place to park is at the church end of the High Street. Opposite the church there's a pub called (I think) The Sun. If you go up the side road from the pub there's a carpark on the right and you can cut through that into the High Street.