If I remember rightly, when I had my mates bumper off the fog lights simply came out of the back with the removal of one screw. As long as you can get past the plastic covering underneath, you should be able to reach up to the wire. And if you can't pop the wire off and replace the bulb, you should be able to undo the screw and drop the entire light down.
The main plastic covering in the middle is secured with about half a dozen screws along the front and sides, I'd start by removing that and see what access it gives you.