... about Georgette Heyer there are 2 interesting books out there that you shouldn't miss.
One is The Private World of Georgette Heyer by Jane Aiken Hodge. Focusing not only in her books but also in her private life, even if the author admits to some lack of information as Heyer was a very private person. It's a well written biography with plenty of information for Heyer fans. If you are new to her work beware that the plots and endings of the books are mentioned and there's a detailed analysis of each one. The author is herself an well known writer and this book was sadly out of print for a while till Arrow decided to reprint it in 2006.
The other is Georgette Heyer's Regency World by Jennifer Kloester. This one reads like a reference book. Covering ever conceivable aspect of the Regency period it mentions social relations, fashion, political and military aspects, town and country life etc etc. The perfect guide for whoever wants to know more about the Regency! If you are already a Heyer fan you will like to know more about the world she set her stories in, if you don't know her work yet you will definitely want to read one of her books after reading this one.
There are also some great resources out there on the web, and here are just a few links!
A Book For All Reasons