TD5 defender Cruise control help!

So I'm moving to the french alps next week, driving down in the defender & really wanted cruise control. I followed the instructions that are posted here there and everywhere online, wired the necessary switches into the ecu but it doesn't work.
I've plugged the nanocom in and it shows the switches working but not quite how I expected, I'm not sure if its just a nanocom glitch (I've got the really basic old one) it shows the cruise control as off when its on and on when its off and the same with the set/res switches they are shown as permanently on until you press one and it changes to off while you're pressing the button which is weird because its definitely wired correctly!
The Brake switch also seems to be the wrong way round on the nanocom, shows on when the pedal is in its resting position and off when its pressed (Brake lights work as normal).
Its a 2003 td5 NNN ecu with a standard defender ratio transfer box.
Anyone got ideas why it wouldn't work? Not looking forward to the 10+ hour drive without it!

All this hassle for one 10-hour trip?

I know but I've had cruise control in my cars for years and once you've had it its hard to live without it :-(
It looked so easy to do as well!