There are thousands of books about WW2 - usually written by officers or academics.
"St Valery: the Impossible Odds" (Birlinn) is an account of the capture of the 51st Highland Division in 1940.
After an admirably succinct and well-illustrated account of the fall of France (including the air campaign), it contains four first hand accounts of life in the POW camps by ordinary soldiers - who had a completely different experience to officers or NCOs. (They had to work 12 hour days on minimum food). It is humbling to read what that fast disappearing generation endured.
It's £7.99 from Waterstones - or available from Amazon (reviewed) from £6.85 upwards - with royalties going to the Erskine Homes for veterans.
For the really stingy there are second hand copies from .01p upwards!