I'm struggling to find a replacement "front fog light switch", so is it possiable to use a "rear fog light switch" instead and then swap just the face of the switch over.

Or are the pins on the rear of the switches diffrent preventing this? 

Also would it be possiable to use a "rear heated window switch" in the same manner, because as far a as I can tell using the haynes wiring diagrams are that these three switches are all the same internally.

Don't think it is possible due to the different wiring to the switches. The front and rear fog lights switches function differently depending on the selected main, low and high beam selection. Forget about the rear window heater switch.

Thanks, I'll keep searching for the correct switch.

The rear fog lamps switch is totally different. But you can use a rear window heater switch. You can't use the original gray mother connector though, you need to crimp separate pins instead. Don't use tin soldering.

I have some spare...