Heidisps Asda do fab christmas blankets - in a really soft microplush. I Santa gave everybody in the house one on Christmas morning along with the stockings a couple of years ago and the dc still have them on their bed - they refused to put them away (even after I've bought more of the same blankets but plain 
). many washes later, they're still going strong. Have already had a request for more christmas blankets from both dc. There are lots of designs - from pugs wearing santa hats to ones with santa faces or ones with jolly christmasy things on to slightly more grown up ones with stars or snowflakes etc on. And usually £5-6 so also bargainous. And you can click and collect them to make sure that they have the ones in that you want to save a wasted trip. (they often sell quite quickly - and even if they get more in, you want them to have the ones you want on the day you want them!).
If you have access to a costco they have lovely extra super soft plush blankets and throws. But plain colours so not very christmasy! Great for the price - about £13 for the throw and £18 for the king size blanket.