I just finished reading "The Longest Afternoon" by Brendan Simms. Amazon - The Longest Afternoon
This is a relatively short (approximately 130 pages), inexpensive ($24.99 retail; less through Amazon) history of the KGL's defence of La Haye Sainte at the Battle of Waterloo.
This would seem to be the first full length treatment of the defence of the farm of La Haye Sainte - Hougomont receiving far more of the "press". Simms provides great backgrounds of the KGL and individuals at the farm that fateful day, and follows them through the battle. While there are limited maps, that can be supplemented by the reader's other Waterloo books (or online resources). Simms has a pleasant and easy to read style, and the pages fly by.
I enjoyed the book, learned more about the KGL than I'd known before, and found myself wanting to learn even more.
What more can you ask for?