I watched the first episode and was a little confused too, I decided I would try the second episode and to be honest I did enjoy it, especially as some of my school history lessons started to flood back. From what I remember Edward the Confessor was basically controlled by his mother, he apparently promised William of Normandy, a cousin, that the throne of England would come to him upon edward's death. When he died in 1066, there were 4 claimants to the thone, Harald Hadrada, King of Norway decided he wanted England, William thought it should he his and our Harold Godwinson, son of Godwin of Wessex, was in line too as a means of uniting Mercia and Wessex and finally completing King Alfred's dream of a united England. Finally Harold G was pronounced King early in 1066, William invaded Britain some months later and a battle ensued, Harold got the arrow in the eye, and William the Conqueror was finally King of England as promised by Edward.
I can't remember who the 4th Claimant was. Edward's mother died long before the battle and Edward was left floundering, trying to run a kingdom he was unfit to reign over. His religion took priority.