Thank you all very much for your help with this. I've just had another few checks of things and discounted an issue with the leisure battery wiring (not that I ever doubted that!) by using some of the original setup, then tried re-seating the motor wires just in case. I then turned my attention to the pod....
I removed the pod from the C5, took the cover off it, and saw that the prongs that you connect the red wire loom to from the back of the unit were actually extended through to the inside of the pod. I connected the red loom to the inside of these prongs (the correct way round) and the motor now works when you press the go button!!!! So despite the outside prongs looking clean, they aren't as clean as the sections that come in through the inside of the pod box. I'm gonna give them a wire brushing when I can get to the garage. I can't believe it's working at last! Well Happy, just a shame it's chucking it down outside so I can't go on a proper run with it
I would like to thank everyone who has suggested things to check and offered assistance. I hope that I can gain a bit more knowledge and help a newbie out in the future. This is easily the most helpful forum I have ever posted an issue on. I think I would have given up before now without the help of you all, so thank you all very much! Without wanting this to sound like an Oscar acceptance speech I'd finally like to thank you John for volunteering to visit the middle of nowhere to help get my c5 back on the road (or Route 51 Cycle track, as will be the case)!