You can buy it from B & Q or order online, I've just used it to strip paint from a door, works wonderfully. Will do 2/3 layers at a time. Is a bit more expensive than other stripers but is non-solvant based and can be used on a huge range of things including plastics.
I'd do a trial area first to make sure its ok on your plastic!
HI..Just to clarify that the product is called Home Strip and not X-Tex. X-Tex is a product by the same company, but it is used to remove artex. You can also find it on the project pages under paint stripping.