Maybe check coolant level first; the cause for such a symptom may be too low
coolant level - it was in my case ;)  (Fiat Tipo).
Klemen

I 'think' I may have a sticky thermostat - Sometimes the temp needle
fluctuates a bit, sometimes stays on the upper range then drops instantly to
normal intermittantly, and usually/normally sits in the normal middle
position.

Is this likely, and how hard is it to change the thermostat - assuming it's
not stuck in the LHS of the engine  !

(Don't think the coolant has been changed yet)

thanks

Graham.