I recommend you download the full manuals and parts list from the web - much better than the Haynes.
pdf Land Rover Manuals | Landroverweb.com
You can buy all the correct coloured wiring from vehicle wiring products. I recommend keeping with the correct colours - because the next time you look at it will make sense. Nothing worse than peering at a collection of randomly coloured wires from a previous owners handiwork!
If you don't already have one, a gas soldering iron will make life much easier. Good luck!