Not used that site but there is an outlet on Ebay (Fashionwize, I think, something like that) that sells them.
I sent for some for dd's but had to return them because they weren't long enough. They were good about refunding promptly, but of course I lost money posting them back.
They seemed ok as shool trousers though (the material is quite stiff feeling though I thought), it's just that my dds are so blimmin tall I needed something a little longer.
But oh the holy grail of grey, skinny school trousers
. It's driven me nuts over the last couple of years. In the end, last year, I bought some (very nice) bootcut slimfit ones from Next and narrowed them myself by taking in the side seems on my sewing machine.