I'm sorry but I don't. The place to go to be saturated in the Norman Conquest, 1066 and all that is Britain (or France). However, I'm told they have now stopped teaching about 1066 in the British schools. Awwwkkk! Something about "dead white males"...
We know the Normans were VERY Celtic, from their Celtic Norse and Dansk roots, to the Celtic French women some of them married. They invaded the Celtic English who had just defeated other Celtic Norse near York. Two battles in so short a time was too much for the English.
One reason we "know" so little about the Celts in general is most everything we know in America is written in English, mostly in England! Most of us don't have access to the huge body of Celtic material written in French, German, and other European languages which take quite a different view of the exclusivity the English claim on THEIR Celts.