Karl congrats on the news.
If you can find a rear shelf to fit its pretty simple.
Firstly check you have cable with a square connector hanging down somewhere on the left hand side at the back of the boot it maybe covered by the boot trim.
This is how I fitted mine.
1. I flattened down the back seat.
2. Release the rubber from around the hole.
3. Pull the rear headrests out from the rear shelf, then twist the central pin off this is what the armrest back locks onto.
4. Using 2 flat bladed screwdrivers one either side of the grey inserts, push in the tabs to release the insert which the headrest arm goes into. (x6 inserts) do not push the tabs in too far as they may snap.
5. There should be a few push in fasteners holding the shelf in position using again a flat bladed screwdriver hook these out, these are usually not seen when the seats are in use. Row of 5 or 6.
6. Remove the cover to the centre seatbelt unit.
7. Using a (19mm socket?) with an extension bar remove the single bolt holding the seatbelt
unit in place.
**Now all the pieces should be clear to pull the shelf out**
8. Push in the new shelf with the blind gradually into position as you need to feed the cable through the top in through one of the holes so that its seen in the boot.
Once the shelf is back in place, push back in the fasteners and the headrest inserts then the headrests, connect the cable up in the boot and put the switch in place.
With mine I didn't need to do any fuses it just worked. Plug and play as they say.
I'm not sure if there is an official guide with photo's but this should give you some idea of what is involved.
HTH