Habitat!!!
They're lovely, but can be a bit pricey. There are quite a few habitat stores about, but the size range varies in each.
They go from fur to silk to cotton.
Other than that, have you tried somewhere like Dunelm Mill or Ponden Mill. Also, Asda, Tesco, Sainbo's do nice little ranges. John Lewis and House of Fraser, Pier (as someone else mentioned).
Although if you can get to an Ikea, their throws are great sizes. I have one that drowns my bed and it's lovely!
Hope this helps,
Jo