Having driven home for the first time with no faults showing themselves I sat in the back on the driveway to see what it’s like. I turned on the rear seats air heater. The motor is quite noisey, is it a case of “they’re all like that sir?”

Post a video, do you mean the rear air heater or rear heater/cooler seats. (if they exist, i don't know about that)
If it is then you might need a new blowermotor, or just oil the bearings but they might be sealed.