England is an older country than France, the very fact that a Norman vassal of the French King could break away and declare war on England independently shows how weak the French Crown was and how France lacked any sense of "Frenchness" at the time. By contrast England was resiliant enough that the Danish Kings were not so much overthrown when Cnut died as simply frozen out by the English Earls and Bishops.
One theory for why the English rolled over after Hastings is that they didn't believe the Normans would last - England would just shrug them off in a generation like the Danes. What they didn't count on was William the Bastard being quite that much of a bastard that he killed or exiled the entire English aristocracy, dethroned all the English bishops and either dissolved or "re-founded" the Enlish monasteries as Norman establishments.
In a way it was the 100 years war that created France, as you say, the French banded together and became defined by their opposition to English rule - throwing off the English yoke was something the French did together.
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