Hitler's Victory

For the same subject treated quite well in fiction, look for a copy of Len Deighton's "SS GB". You follow the path of a British cop who has to answer to Nazi officers as he first investigates, and then is drawn into, a resistance movement. The resistance schemes to draw the sympathy of the isolationist USA, looking for America's intervention in the European war. This could help you flesh out some of the concepts in "Hitler's Britain." And, frankly, I'm a bit annoyed with the summary that suggests a likely ineffectual British resistance. That scarcely jives with the Brits who survived the bombing of London, and who rescued the troops at Dunkirk. For those of you who know Len Deighton's work, you won't be wasting your time, if you can find the book.