DICEGEORGE wrote

I seem to recall reading somewhere that in 2 way switching
for house lighting its a good idea to have a neutral wire
parallel to the lives to cut down on interference, is this so?

Nope, its an urban myth.

In which case I need 4 core and earth not 3 core and earth.

Yes, and that is available.

I is mentioned at:
http://wiki.diyfaq.org.uk/index.php/2_Way_Switching

Its bull****.