Hi, the reason I asked what part of the UK, A search for a Land Rover Mechanic. You Husband need to replace the Thermostat regards the heating, the car is getting on a bit, you have not stated the mileage so I presume the car has done 100000+ miles, to start from scratch, flush out the Rad & the system, re-fill & don't forget Winter/summer antifreeze, replace what I have stated & I Suggest a new Temp Sender they are not that dear, start the car up & bleed the system have the Heater on & in the HOT MODE, Leave the car running check your temp gauge the heater should start to feel warm after about 10mins keep checking your temp gauge, If all seems to be ok take the car for a local run to try out, this way you are eliminating WHAT could be wrong, if the car is NOT USING WATER I doubt it's the gasket, I'll check your responce.