2004 Vauxhall Vectra find fuse that protects rear fog lights

I'm not sure the fogs will be fused as such but if it is they are quite often fused with another circuit and not necessarilly mentioned with the fuse list, check all fuses with a test light, if your fogs not working make sure you have the right bulb fitted by checking the bulb fitting, ie single/double filiments or single/double contacts

Left hand rear compartment hold the REC, rear electrical centre, the rear lights are fed from there.

Does the warning light come on?.

If your offside fog light works and you are trying to get the nearside one to work, then this is normal. As the nearside is not wired as standard manufacture...