Thanks for that helpful advice.
Just one other thing I wanted to ask.
Does the low voltage transformer have to be wired into the light circuit,
or, is it ok to run it from a mains FCU, and if ok, what happens to the wiring regarding the Switched Live.
Does it mess up the timer etc...
Please bear with me here.
3 grey cables meet at the bathroom light pullswitch.
3 black wires are twisted together and covered in black tape.
3 Green/stripe wires go into the backplate earth terminal.
2red wires go into one two of the switch terminals and
1red goes into the other...