I found - and purchased - a National Lottery Advent Scratchcard!
For a few years in succession, I would buy a card and scratch off a window a day leading into Christmas. Then - for some reason - I couldn't find them in any of the shops where I purchase scratchies.
Either that or they weren't released by the National Lottery (Someone from Camelot told me they were definitely produced in 2016, but I still couldn't find them a year later).
What I do know is they have been released for Christmas 2018. And the card is already where previous cards spent Christmas at my home - on the door ready to be scratched.