Yes, you will get more than you already have. For instance any promotions, training courses, possibly spells in hospital (common when men first went to the Middel East). There may be indications of him returning home on leave and so on. If he was married, then you will get the full date and details of where he married and to whom. Any children's names will probably be redacted on the basis that they may still be alive.
There may or may not be an explanation for why he changed Regiments in 1939 and ultimately ended up in the Pioneers.
His first date of service (15/07/1939) is interesting because it is before the general mobilization of the Territorial Army, and long before any conscription had taken place. But I think he must have been in the TA. If he was at Dunkirk, that was after he had been transferred to the Royal Scots Fusiliers. I would guess that he went to the 6th Battalion which was the only one of the R Scots Fus TA battalions which went to France in 1939/40. If by some chance he was with the 2nd Battalion (regular) R Scots Fus, he would have been among only 40 individuals who came back from Dunkirk, the remainder being either killed or captured.
Anyway, there is no need for me to speculate - when you get his service record you will get all these details.
