Got Christmas out of the way and have had the X in the shop.
Garage have diagnosed it as the actuator for the transfer box.
£600+ from BMW so tried the actuator gear replacement that seems to be all over the internet but there was no issues with the original gear within the actuator. Garage have tested and re-calibrated it and the actuator motor appears to be working but the lights are still present.
I have had the steering angle sensor checked and there are no errors so I think I will try the wheel sensors next...
Just posting an update for anybody else with the same DSC/ABS problems.
Thanks.