I guess you will have had to book on Disney.com to stand a chance of getting one. Doubt they will send to anyone who has used Dsiney.co.uk
I have booked cruises with Disneycruiseline.com, Hotel with Disney.com, and had Annual passes(purchased thru a Cast member) so it could be thru any of these routes. It came thru an email address I doen't tend to use much, certainly not given it to Disney in past couple of years, maybe thats why they sent me code, get me to book again thinking I have stopped going.