Spike wrote:

And how do I disconnect the plastic from the mains? The connectors are all
push fit by the looks of things... do they come apart easily? If so, how?!

On the stuff I've used, there's a collar around the mouth of the fitting
which you push inwards slightly, which makes it lose its grip on the
plastic pipe, which may be withdrawn. Happens very easily; no need to
force it, and if you do, something will break!

I'd recommend you buy whatever new pushfit kit you need to do the job
and have a good play with that before you start trying to dismantle the
existing system - that will be much easier to do once you have a feel
for how the fittings work.

David