There you got then, you can get a horn for about 10-15 Quid! is the wiring there? if you want a wiring diagram or pics let me know. By law car need's a rear fog light, it could be someones removed it or it go damaged and was removed, but by the look's of it say's in your first post 'wrong colour' it's probaly got the wrong bulb in there! i would have a look first. If you get stuck, take a picture of the rear and we can check the rear fog out!