On Thursday I got not only a postcard but also three covers including one from the United Kingdom.
With awesome stamps:
Post and Go - Game of Thrones (whole set) (issued 23-01-2018)
with a First Day Special Postmark from Belfast
Inside was an information card about Game of Thrones.
Already on Wednesday I got my ordered Game of Thrones stamps from the United Kingdom. You can see close-ups of the stamps here.