I can't recommend too highly the most recent pair of novels by American writer Connie Willis.
Blackout and All Clear form a single, long story in what is sometimes referred to as Willis's Time Travel Series.
The common link of the series (which also includes historical novel The Domesday Book, romantic comedy To Say Nothing of the Dog, and short story Firewatch) is the idea that Oxford historians in the mid-21st century have time travel. With certain limitations they can travel back in time to observe and study events.
History itself seems to have some kind of protective mechanism, though. Unpredictable geographic or temporal 'slippage' seems to prevent historians from getting to certain key events whose alteration would significantly affect future history, whilst remaining in the past long enough to coincide with your future self on another time travel mission is invariably fatal.
As the covers and titles suggest, Blackout and All Clear are focussed on the British home front during the second world war. Four young history students study, and become drawn into, the lives of civilians, evacuees, and D-Day preparers during the course of the war. When it becomes clear that something has gone very wrong with their ride home, they are forced to share more of the danger of war than they bargained for.
Willis's books tend to have a mystery element. We and the characters suffer information blackout for much of the story but all is satisfyingly clear at the end.
Mainly, though, this is a story of heroism; the understated heroism of ordinary people in extraordinary circumstances. Something the historians intend to study but of which they eventually partake. Given Willis's obvious Anglophilia and keen eye for detail I'd recommend these books to anyone with an interest in British life during the first half of the 1940s.