Hi Fellow Salopian,
The D2 does not like to have a cooked engine and it's a bit worrying that this is not the first time. Also the temp guage is not very accurate, and by the time it has gone into the red it's usually too late. A good garage should be able to pressure test the coolant system and do a "sniff test" for combustion gasses in the coolant.
Good luck,
Griff