Brilliant, thanks Roverlike. 
The info you provided includes Additional Relays and the relay I was wondering about is an 'Air Conditioning Pack Relay Module" which controls the radiator fans + the AC compressor clutch, the items which have failed. 
I imagine the relay will be easier to find either new or second hand and will certainly be easier to fit and less worrisome than the ECU sets.
I'm very grateful. 2.png

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