Certainly Shawn's book!
I also found First Light by Geoffrey Wellum an extremely good read - it's the equivalent of Chickenhawk for Spitfire pilots.
Talking of spitfires, Dark Blue World on DVD is also recommended. Tells the story of 2 czech pilots in the RAF during WWII who fought bravely yet ended up in jail in their own country because it was thought they might rebel. They fall in love with the same women, and purists will notice an unholy mix of spitfire marks in the same squadron, but the photography is excellent - a lot better than Battle of Britain.
Phil