I just wanted to recommend some historical novels, which I find are excellent evocations of a medieval mindset and cracking good reads as well.

Basically, anything by Alfred Duggan. Some of these are out of print but are readily available second hand. Some have had more recent editions.

Just off the top of my head, the following are the medieval ones:

Knight with Armour
Leopards and Lillies
Lady for Ransom
Count Bohemund
Lord Geoffrey's Fancy

They are exceptional.

GR

I will add to this:

Sharon Penman is a superb author. She really brings the medieval period to life. Sunne in Splendour is her take on the life and times of Richard III and is a gripping read.

Elizabeth Chadwick is another great author. She wrote 'The Greatest Knight' about William Marshal, who has always had the reputation of being the greatest knight to ever live. 'Scarlet Lion' is the second and final book about William Marshal.

Obviously Bernard Cornwell. His Grail Quest trilogy is a cracking read.