A Piece of Cake — Derek Robinson

From the Phoney War of 1939 to the Battle of Britain in 1940, the pilots of Hornet Squadron learn their lessons the hard way. Hi-jinks are all very well on the ground, but once in a Hurricane's cockpit, the best killers keep their wits close.
Newly promoted Commanding Officer Fanny Barton has a job on to whip the Hornets into shape before they face the Luftwaffe's seasoned pilots. And sometimes Fighter Command, with its obsolete tactics and stiff doctrines, is the real menace.
As with all Robinson's novels, the raw dialogue, rich black humour and brilliantly rendered, adrenalin-packed dogfights bring the Battle of Britain, and the brave few who fought it, to life.