Part 2 never really happened.
It turned out the boss adapter I had was a different size to the hole in the steering wheel so my mate made up a couple of slabs of alloy to connect the two together.
The horn is now a discreet button in front of the ignition key. Great for MOT but less useful when driving.
The other bit I don't seem to have any good photos of is removing the airbag trigger from the centre console. It was when I removed this that the airbag light stopped lighting up.
In this photo is it the bit labelled BEHR in white and yellow. It simply unbolted and unplugged but as you can seer, I had removed most of the centre console before this point