Two best WWII books (for overall war, rather than specific battles).
The Second World War, John Keegan
The Second World War, Martin Gilbert
Two of the UK's finest historian, both give great coverage. Gilbert's book gives a lot more detail and it's about twice as thick.
John Keegan, unlike many other authors, includes the effect of the Allies breaking the Axis codes in his analysis. And Keegan's writing is terrifically readable.
Pat Buchanan's work is indispensable
:Churchill, Hitler, and "The Unnecessary War": How Britain Lost Its Empire and the West Lost the World
https://www.amazon.com/Churchill-Hitler-Unnecessary-War-Britain/dp/0307405168And if you really want some of the real, primary sources, David Irving is the man who dug them up.
http://fpp.co.uk/https://irvingbooks.com/xcart/An example is HItler's War
https://irvingbooks.com/xcart/product.php?productid=18101&cat=0&bestseller=YChurchill's War, vol i: The Struggle for Power
https://irvingbooks.com/xcart/product.php?productid=17896&cat=0&bestseller=Y