Sorry to confuse you, Cucumber. I don't expect to pay £6-7k for a bathroom. I expect to pay around £11-£12k for three rooms: bathroom, en-suite, downstairs loo all in.
Bathroom sanitary ware: £1544.56
I'm having a mixer shower over the bath, wall hung toilet and basin with semi-pedestal.
Ensuite: £1699.22
Wall hung toilet & mixer shower again, sink in wall hung unit
Cloakroom: £601.91
Toilet & sink in separate units
Plus a shower pump at about £150
And mirrors which can be cheap/expensive
Wall tiles: a bit under £1000
for fully tiled bathroom, just the shower and splashback in the ensuite and splashback/windowsill in cloakroom
Plumber for all three rooms: £5100
Includes knocking down and re-building new stud wall in ensuite, adding toilet where wasn't one in ensuite, all the tiling, plumbing materials etc
Will need to add cost of electrics, waste disposal and painting, but these will be done by builder/tradesmen already in the house doing other stuff. Also need to add cost of karndean flooring.
Prices include VAT where applicable.
If I didn't have other tradesmen in and skip in front of the garage, I'd be looking to spend a bit more. I think I am getting a good price as I was budgeting around £15k initially.