The water in the cream tends to separate out on freezing. If you freeze a whole sealed carton, you can shake it after defrosting to mix it up again. Cream is notorious for picking up smells or flavours from anything else in the freezer, and it's recommended to put it in a couple of freezer bags, even when it's still in the sealed carton.
I posted a similar question about the lack of frozen cream, and was resolutely informed by fellow ABers that it was no longer available.
Iceland is the one supermarket that I have not checked - thanks for the tip off dzug!