Can anyone recommend/suggest an online store which sells HL compatible wires? I need to extend some of the wiring to move the on/ off switch etc but live in the middle of nowhere!
I don't know of anywhere in the UK. The best place for wiring is http://www.rctank.de/. They were pretty quick to deliver to the UK. An alternative is asking Forgebear on Ebay if he can get the parts you need.
Ali express has the wiring set. So do ozarmor and tankarmy. Other then that I use 18 ga. Wire and a lot of solder less connectors and shrink tubing.
If you want a neat job there is a lot of soldering to do. It's not rocket science but I find it tricky even so. Practice first and make sure you have all the proper supplies including flux and a proper wire holder for soldering. Also keep an eye on the iron a lot of melt marks on objects in my studio apt/flat/dump testify what happens when you let the bloody iron roll around after putting it down.