One that caught my eye was by Vanora Bennett, The Queen's Lover, which is a novel of Catherine de Valois, widow of Henry V, and Owen Tudor, to be released in March (it is titled Blood Royal in the UK in April 2009).
Vanora Bennett has written Portrait of an Unknown Woman, and her second novel is Figures in Silk, which was a hit this March. Have you read these works of hers? I have the first but I haven't gotten to it. My mother enjoyed it very much.
Preorder the newest novel via Amazon, or sign up to be notified when the Book Depository has the UK version in stock.
I am also looking forward to Kate Emerson's Secrets of the Tudor Court: Between Two Queens coming in January, and for something different: by Chris Greenhalgh Coco Chanel & Igor Stravinsky, which is a "romantic tale of Coco Chanel's illicit affair with Igor Stravinsky, set in 1913 France".