When working on my hand brake today I noticed a blank white/grey plug hanging down below the steering wheel, just to the left side of the fuse box. should this be pluged in somewere and whats it for? It was getting dark when I spotted it so could see very well for other side of a plug.

If everything works, and you can't see a connection nearby then don't worry, probably just a bit of wiring for an optional extra or piece of equipment on another version. Harnesses typically have extra bits in them to avoid the hassle of a dedicated loom for each spec, makes it less hassle to order and supply, plus it means retro-fitting certain trinkets is a lot easier if the plug is already there.

Check the colours of the wiring in the light and match them with the RAVE diagrams