well if they replace the waterpump with the 50k service yes if not you can do it yourself will cost you something in the regions of 80 quid incl some hours to change all filters, all fluids, sparkplugs and all brake pads.
I would check the timingbelt first to see if there is any weird wear on if yes, you might be better of just getting them to do the timing belt & water pump at the same time.... (also for OEM parts the prices are quite right but DIY makes owning a IS200 a lot cheaper)