Wow, 3 months and a week later, I finally got chance to fit my new home-made partial loom and it works! Phew. Also had to pop out the piston and replace the dust boot as that had ripped somehow (on left and right sides)
Had to remove the rear wheelarch liner so cleaned that all above and behind it with pressure washer. Found the accululator on the air shock was a bit rusty on the seam so put some anti-corrosion wax on it.
A couple of panel clips broke, the part number is 4D0807300
Attachment 18279
Attachment 18280
New cables were insered into gland just behind damper which is next to plastic vent in the side triim of the boot interior and can be reached by hand and pulled - only had to remove navi/TV access panel.
Then routed behind plastic boot slam panel trim and to EPB control unit uner the battery.
When I popped the pins out of the large connector on the EPB ECU, the contact was a different design that those I had bought, so I cut and soldered to the existing wires. (two thick and two very thin for the hall sender)