The overheat cut out has started to operate on our Potterton Prima 40F gas
boiler. It restarts and operates fine after resetting the cutout after
allowing time for it to cool down. This happens a couple of times a day.
Does this mean the boiler thermostat needs replacing? or could there be
another likely cause?

Is it a job I can do myself? or de we need a professional?
Any ideas of likely costs for repair and boiler service?

Any advice will be appreciated - any good boiler repair chaps in the
Bolton/Wigan Area?

Cheers - now off the pub