I know of a tradition among British patriots where they invite the HRM the Queen or the Prince of Wales to their wedding. So how many do they get each year?
1. If you are really serious about getting an answer, then you need to contact the Public Information Office of the Royal Family. The contact details are in this link.
http://www.royal.gov.uk/output/page249.asp
2. I have never heard of this alleged tradition. You may have been misinformed.