Found this site and a good price but I wonder if it is for 20kg bags! postage is cheap too anyone used this site?
http://www.willowbrookequestrian.com/shop/catalogue.asp?p=39&g=16&d=53&c=&s=&f=&b=0
http://www.willowbrookequestrian.com/shop/catalogue.asp?p=39&g=16&d=53&c=&s=&f=&b=0