O.K, onwards and upwards with the tear planning, I have another of my questions!
I only have a very basic understanding of electronics, so I am gonna get my electrician mate in to do all the electrics but I'm still curious!
Regarding batteries, can you connect two wires at once to them, for example the charger leads and the wire going to the distribution station/fusebox (see diagram!) If this is possible can these two wires both by put into one of those easy release clamps for the battery?
Grounding the 12v, do I do this like a car radio installation and just get it on to a bare piece of metal? (eg chassis) Or do I have to put the wire physically on the ground when I pitch up (like a trailing wire).
Most of the other stuff I'm okay with - wiring up the sockets and lights etc, so maybe if I find the answers to these questions I can do the 12v, and just get him to check it!
Not touching the 240v though - I'll leave that to him!
Quick thanks to the author of this diagram as well - its very clear and I've fiddled with it to fit in with my plans!
Connecting two wires to the battery diagram: