The Charlton guide lists birth year notes as being in the format 000XXXX, where XXXX is any year from 1900 to the present year.
Your notes would probably be called "birth DAY notes" because they refer to a specific day. But Charlton does not have a listing for these in its catalogue. I guess what they are worth depends on what an interested collector is willing to pay. It'll be much harder to find a premium-paying buyer for your pair of notes than if you had a note in the format 0001984, for example!
As for your 12th July 1984 note, perhaps contact this guy as a potential buyer:
http://en.wikipedia.org/wiki/Michael_McGovern