Guys; thanks for your comprehensive replies.
Wow, that looks like a large job for a £30 part and shows my dealer's quote of 4 hours was very reasonable guess of the time involved.
Looks like I'll do without for the time being.
HOWEVER, I see reference to checking temperatures with VCDS. As I have a 'floating' panel gauge [temp drops down below 90 - never above], I'd like to see what the 'real' temperatiure is.
Which ECU[s]/Measuring block[s] will tell me what the car thinks the temperature is?
Thanks & Regards - Julian