Morrisons, Tesco and M&S around here don't have them. I asked in Morrisons and the girl didn't seem to know what I was talking about. They all had them last year.
M&S had one which I used last week. It took a bit of finding but it was the usual Woodland Trust collection. Worth asking in your branch in case its hidden
If you put them in the household recycling bin you'd have to remove any non paper additions like glitter or foil, but you can chuck them in just as they are at the collection points; plus it helps raise some money and replant trees.