http://sill-www.army.mil/FAMAG/archives.htm
The US Field Artillery Magazine archive. A quick scroll through the pdf's of 1940 gives some contemporary accounts of the fall of France and Dunkirk, plus coverage of German articles about the 40-41 period.
Nothing specifically Canadian or Commonwealth, but loads and loads of background info, contemporary pics, and a great explanation of the US decisions on truck types in 1939 and 1940.
If you find anything of real interest cut and paste the url here;
DUNKIRK ARTICLE
Of course it had to be an Australian, Dave Robinson, that pointed me at it.
Gordon