Hi Spike

But I have no idea how this new fangled plastic stuff works.

So how would one go about putting a T piece style connector in?

Simply go and buy a plastic T piece.

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?!

The ones I've used have a ring where the pipe enters the fitting - just push
that back towards the fitting.

Dave