Thanks, useful information, and it looks like I am on the right track. I am by no means a confident electrician but I was thinking about concealing a fused spur near the base of the linen cupboard. There is a 3 pin plug attached on a short lead on the heater so I will have to cut that off. My main concern was linking to an existing power outlet I didn't want that to be unsafe? I wouldn't have given it a second thought had it been house wiring.
What I think I will do as an interim is try a temporary installation just to see if the rail is any good or then post my observations on here in case anyone in the future decides to go down the same path.