This was easier than I thought, luckily someone had already installed the power on a separate fused circuit and the switch was wired in too. All I had to do was change the face plate for a socket and mount it properly to the wall.
Existing pipework removed and new socket installed and tested.
The mounting bracket installed underneath sink.
New garbage disposal installed in position
Luckily I had enough pieces left over from the original pipework to finish off the drainage and connect the dishwasher
Job done and Mrs P over the moon, and I quote this is what "sorts the middle class from the lower class".
