Well, first job on out disco2 is a 12s socket. bought the kit,prewired socket no prob, got the tec3m relay to switch fridge etc, but am getting confused with some wires Relay has two 12v connectors, I know one comes straight from battery via fuse,what about other 12v connector? numbers 3 and seven on socket are earth, can they be put together and bolted to bodywork,relay has an earth connector, does that need to be linked to 3 and 7? Number 1 for reverse lamp do i pick up the wire from disco loom and scotchlock?

Is the other 12v +ve for the alternator so it knows when the engine is running and so it will split the charge

The earth ones you can use bodywork but make sure it's a good earthing point... Maybe bolt it to your towbar ....

http://www.landyzone.co.uk/lz/f9/towbar-fitting-instructions-51094.html

don't forget your 25amp diode.