I had them changed by a workshop. There are so many on Ebay that have broken mounts I figured that it couldn't be obviously straightforward- to get away without having a little knowledge.
In the meantime I got myself a Haynes manual. I guess the reason for so many having one or more broken mounts is that you need to undo parts of the front bumper to access and remove retaining screws there. Not rocket science, but you need to know where to look- and I guess some people are too impatient when it doesn't come out with all visible screws out, and end up using brute force. Not advisable if you want to sell your used lamps though...
I would assume you'd need a couple of hours with your own tools and layman's knowledge. My workshop in Germany charge me an hour's labour to switch them over- and they didn't need to refer to the manual.
There's no reason why not to try it yourself, but some of the screws/bolts are in awkward (although not impossible) places to get to.
As far as the rear fog light goes, this is easier. You need to switch sides to the opposite light cluster. Quell surprise, and the light bulb is already there for you, but the cabling is missing for the power to reach the lamp from the main wiring harness in the boot. Go to the side where your fog light currently burns, and remove the bulb. 2 fog lights are allowed, but if both are running they are not very bright, and probably won't pass French MOT. Trace the circuit board back to the connecter to the harness to see which pin it was connected to.
Cut a piece of electrical flex about 2 meters long (you need about 1.5 m, but this gives you more flexibility in passing the wire through the boot). I used an old 240v cassette cable I no longer needed, and spliced it so I only had one single cable. You need cable to carry the load, so don't use anything too weedy. There are a lot of Amps in the 12v so you don't want cheap speaker cable which might overheat and short out on you.
Connect the one pin into the connecter for the UK fog lamp side... (from the bulb you just removed). Now feed your cable as best as possible through from one side to the other. I ran mine through the hatch where the spare tools can be kept just inside the boot. There are other cables also running there to tape the new one to. When you have the cable on the other side, feed it up to the wiring harness attachments, and look on the lights to see which slot has no cabling joinging the back light. Better still, take out the back light, and follow the circuit board from the fog lamp back to the right pin. Wedge the cable into the fitting and insert into lamp cluster.
Before you put lights back, you might as well check it works. If it doesn't then you'll save time fiddling around finding the right slot with the light cluster not mounted, rather than have to remove and look again (as I did the first attempt).
With hindsight, this job took me less than an hour, of which at least 15 minutes was looking in the basement for an old piece of electrical flex to use... Easy for a novice without more than a screwdriver. No Haynes necessary.
