I will plug The Splendid and the Vile by Erik Larson again. It's about Churchill's first year as PM. While mountains have been written about Churchill's life, this is a focus on this one sliver. To me the most interesting parts are his ability to see certain strengths in people and put them in key positions, and the battle of wills between Churchill and Hitler. Erik Larson is the author of Devil in the White City and In the Garden of the Beasts among others. He's very readable and good at capturing personalitites.
I've read a ton on Hitler and I cannot understand why he stuck with Goerring as long as he did. Goerring was an early Nazi with him and was a WW1 flying ace. But there were plenty of other early party members Hitler ditched over time. Goerring made huge errors in developing and deploying the Luftwaffe. Had Hitler had a competent head of his air force, the Battle of Britain could have taken on a very different tone.