SOLVED IT MYSELF!!!
I intercepted the wiring loom in the boot near the rear of the drivers side brake light. Follow these steps:
1) You need to just pull the carpet cover away to gain access to the corner of the car. It simply pulls out and pushes back in when you are done.
2) You should now see the wiring loom, it may have black tape around it so carefully remove this so you can see the wires. This wiring loom has about 20 wires of differing thickness and colour and is easily visible.
3) The one you want is black with a white stripe running down it. Mine had a very thin white stripe and at first I missed it so look carefully. This is the LIVE for the reverse light!!
4) You can join to this wire any way you like, I used a cable connector but I suppose you could expose a bit of the copper and twist into it (insulating it afterwards of course).
5) The earth for the reverse light is black with a purple (pinkish) stripe but I actually put a self tapping screw next to the wiring loom into the car and put the earth wire around that.
That's it, job done and parking sensors fitted and working when you reverse!!