I don't mean to put you off having the car fixed ... not in any way ... I just don't want anything daft to happen on the way to getting the fix !!
The Green Flag option if available is the easiest, next would be a trailer move, after that the long slow drive.
The fix is probably not difficult ( I don't subscribe to the HG failure -if the car runs OK its probably not a HG) - but its just amatter of logistics...
Once sorted you'll have a car to enjoy and be proud of 
There are many ways a headgasket can fail, it does not have to involve the fire rings!
I agree entirely, however, you guys did the thermostat at Shifnal and found evidence of bodged oil cooler work before.
1. I reckon you would have seen signs of HG problems, and reacted accordingly
2. The coincidence of the HG going after a thermostat change is too extreme, and to go and only leak coolant takes that a step too far for me ...
3. The chance of the "bodge" being disturbed by the thermostat change and now leaking is far more realistic IMHO
I'm probably wrong .. but my money's on the oil cooler !!!
