Whilst I was a wee bit too young to remember Court Line I did purchase the book From Take-off to Touchdown (having witnessed a Court Line staff re-union at the former spectators building around 1994 period?) which is one of the most interesting airline books I have ever purchased, however I thought I might advise your group that Luton Culture have recently released a book written by Peter Simpkins titled London Luton Airport-75 years Anniversary Book.
There are plenty of pictures covering the 30's til the present day.