About a year ago now I picked up a couple of armies for the Hundred Years War from Black Hat Miniatures. It's not really my area, and my usual method of sorting myself out (that is, 'consult appropriate WRG Armies and Enemies books') will not work, because finding a copy of the Armies of the Middle Ages is a bit of a tough ask.
In an effort to make some progress I decided to ask the good folks at the Society of Ancients and more good fellows on TMP for some assistance in choosing books to help a brother gearing up to paint.
After some very helpful suggestions, I've ended up plumping for the following:
The Armies of Agincourt, The Armies of Crecy and Poitiers, French Armies of the Hundred Years War, The Armies of Medieval Burgundy - all Ospreys - and a one-volume history of the war, The Hundred Years War: The English in France, 1337-1453, that was recommended by a kind chap on TMP.
There have also been some excellent internet resources suggested, and I'll link to them now so that I don't forget, and because they might be useful for others as well. Thanks are due to Duncan Head and Anthony Clipsom for suggesting these.
Period illustrations are here ("Armour in Art" section as well as manuscripts) and on Druzhina's site here and, for example, here.
Flags are here and can be used for coats of arms on surcoats and shields.
Historical articles can be found here, and include some famous names.
The Internet Achives site has downloadable versions of Froissart, and I must particularly thank Jarrovian on TMP for bringing him to my attention.
Books to look for in future to help with the painting include Funcken's Age of Chivalry 1, the Almark Agincourt book, and Friar and Ferguson's Basic Heraldry.
For the history, Jonathan Sumption's series comes highly recommended, as do a couple of other books, The Agincourt War and The Crecy War, by Alfred H Burne.
So that gives us quite a bit to go on. The Book Depository order should be here in time for Christmas, so, all going well there will be the chance for a bit of learning to go on!