Most of the time when I put the Furball into reverse the reverse lights don't come on. Occasionally they do. It's not the bulbs or anything like that as I have swapped my standard lights for lexus style lights and the problem is still the same. Does anyone know what this is as I need to get it sorted before I reverse into something in the dark?

Sounds like the gearbox switch

Yeah it will be the reverse light switch , Ive never had to have the Fabia done , but I had to have one fitted to my old Polo.

I've had the wires to it break on an A3- it's very common on Golf IV based cars.