The early MK1's don't have the wiring already there whereas the later ones do, check behind the front fogs to see if the wiring connectors are there, if not they are easy enough to wire in, just one wire to run into the engine bay from the switch and a take off from that wire needs to go to the extra warning light.
My car needed a new bumper so I thought I would upgrade to the fog light one.It is a N Diesel and they will need to be wired up.I was about to ask how to do this when I saw this post so my question is could I get a little more detail on the wireing please? You say one wire to the switch and they will work.Does the live and earth run through the switch then?
The power only runs from the switch, look at the multiplug for the light switch there is one pin unused, this is where the power wire to the front fogs comes from, the fogs themselves are individually earthed (use the earthing points behind the headlights)
From the wire that you run to the fogs you will need to have a take off to the warning lamp (if you only have the rear warning you will need to get hold of a front and rear warning light unit)