Any tips for a task like this?

Drain what water you can from the system by conventional means, then arm
yourself with lots of old towels and some small shallow trays if you can
find any that fit (foil food trays can be good) and a bucket. Line area

Cheers John - I was afraid that might be the case :-). Think I'll put some
plastic sheeting under the towels too - just to be on the safe side. I've
got approx 4" between the pipes and downstairs' laths so should have enough
room for the trays.

Just thinking, I've capped off the old kitchen tap pipes which are in the
same room (kitchen becoming bathroom) - these need to come out 'cause
they're in the wrong place but I've just put compression fit end-caps where
the taps used to be for now. I wonder if I turned the water off, opened the
current bath taps (bathroom becoming kitchen) and removed the end caps from
the old kitchen taps whether I could blow some water out the system? The
pipe run between the two points is probably about 15m. Or is this a silly
idea?

Andy