Thanks for the reply.
Blimey that is an awful lot cheaper than I had been thinking. I would do the new boxing-in and decorating but would be after a plumber to do the pipework.
I was thinking of moving the boxed in section from the kitchen to the living room (the other side of the wall)...
The waste pipe currently goes from the bathroom to the drain via a boxed in bit in the kitchen. This is a bit of a pain as it robs cupboard and worktop space. We're going to be having a kitchen refit and would like to lose the boxing in. It would be better if the boxing in was moved to the other...