I am trying to wire in a replacement switch that has a neon indicator built in (a fused 13A switch). This is so I can tell if the lights have been left on in the loft - the light switch is outside the loft. The existing switch is a one way one. Any ideas?
IF you already way a standard switch installed and it's a straight swap not too difficult, the one thing is that is a light circuit so 13amp fuse rating is not recommened. I assume that the switch being replaced is part of a exsisting light circuit, if the loft lighting does not exceed 6 luminares (lamps/bulbs) i'd use a 3amp fuse.
you'll have a supply and load so your line/live/phase (red/brown cable) will be supply side and load will be black/blue cable.
Remember to be safe, isolate circuits prior to any work and assure the circuit is dead before you carry out any work.