I think Nevaplast is used more in Europe than the UK, but I could be wrong. There are a few different types of plastic used for artificial slopes.
Liberty in Lynchburg, VA has had a year round slope operation for several years. Plastic with flowing water. If you fall, you get wet from what I hear. They teach college PE classes for skiing and boarding during the school year.
As for Xanadu, it transformed into American Dream. Going to be built by the company that owns and runs the Mall of America and the even bigger mall in western Canada. Latest news is that the sale of $1.1 billion . . . yes BILLION . . . is bonds was completed. That means the almost $3 billion of financing to move construction forward is complete.
http://www.wmbfnews.com/story/35729577/american-dream-completes-277b-construction-financingThe skiing/boarding at American Dream will be on manmade snow, not plastic.