I feel sure this must be in the FAQ somewhere, or in the archives, but I
can't find the answer...

I have an Ikea light (a LEDING its called) that I need to fit to a cieling
rose. There are two sets of wires in the ceiling: one I assume is the
switch, the other the mains (each have L/N/E wires).

The light fitting has three wires L/N/E, and that's it. No block like you
normally get with friendly labels on.

So, my question is: what wires do I fit where? I assume the earths all go
to the same place, but what about the rest?

I think part of the answer is going to involve finding which cable is the
switch so I can wire the switch return correctly, but after that, I'm stuck

Any help appreciated!

Jonathan