Thanks for the replies.
I had a price back today from my local garage of £675 to replace the water pump, not including the thermostat & £308 to supply & fit a stock bmw charge pipe, both prices + VAT which works out at £1180
ML Performance are selling a VRSF oem replacement charge pipe for £166, which seems reasonable although a additional £10 for a new o ring seems a bit expensive.
Am awaiting a price back tomorrow from my indie, he told me it isn't necessary to replace the thermostat when changing the water pump, last time the pump was changed BMW Cooper told me the stat had to be changed at the same time regardless but then I suppose the stealers would say that.