I've lived in the UK all my life and have been into origami for a long time. But up till now, my main source of paper has been origami-shop, which does not provide me with a bunch of the papers im desperate to try (no offence to mr. nicholas terry, there is still a wonderful range of papers). Whis is why I just thought I'd post the results of a long time spent searching for places in the uk with the papers I want:
John Purcell paper- I only recently found this place, and although you cant order online (I dont think) UK residents can order over the phone. I wide range of korean, thai, japanese and other papers, in fairly large sheet sizes. I haven't actually checked out the prices yet so yeah.
http://store.falkiners.com/store/- A great store. They take online orders and have a huge range of papers (but sadly no korean hanji). Prices seem about right too.
So , this was just to help out any budding new origami enthusiasts wanting to try out new papers, or for more experienced folders, tired of paying huge sums for shipping costs from america (it costs a lot to ship to the uk).