I ended up stripping out the glove box and side panels in the footwell , I could see the cable still attached to the hot /cold flap so it must be control knob end , this means stripping the dash , radio removed and filled the guide on here to get to change the lamps in the heater control,
I found that the spring clip that holds the outer cable cover had slipped , this ment that the 2 screws under the control panel had to gone out to release it , once loose it took a lot of swearing and big hands in little spaces to turn the control panel around enough remove the clip , replace the the cable into place and then squeeze the securing clip into place
You have to be careful how far you turn as you do not want the clip spring off the other cable
Lamps changed at the same time
In total took about 1.5 hrs as fumbling around for the first 30 minutes but if I had to do again it would be a lot quicker