There's a Christmas Pug duvet, and a gorgeous Christmas Pin Up, which is also available in double and king for a little bit more (£12/£14). The Snow Scene Duvet* for a cot is just £9, and Little Miss Duvet Set* is £10 too.
I guess since you're only using these for a few weeks of the year, you wouldn't want to spend a fortune on them, so these are ideal.
Of course there's always good old Elsa and Anna to fall back on, but they're up to £18.
A nice way to build up to Christmas, methinks?
Thanks to MissBint at HUKD