Shouldn't your client provide you with some material? I was going to recommend Jim Bradbury's book on the subject, but I guess you probably don't want to read a whole book for a bit of info, so iirc their is a French website called something like Early Emblazon? that I seem to remember I looked at a few years ago and it had some info on this period.
I remember it was a bit 'buggy' so maybe make sure all your internet security what nots are up to date, before embarking...
If you use the lead adventure search facility, you may find that you can get more info on the site, as it has been mentioned on here a few times
Sorry I cant be of more help, best of luck with your searching
