I googled surfing in Britain as part of my trip, and these came up
fun:
http://news.bbc.co.uk/2/hi/uk_news/wales/7750743.stm
nuts:
http://news.bbc.co.uk/2/hi/uk_news/wales/7735242.stm
http://news.bbc.co.uk/2/hi/in_pictures/7735525.stm
insane:
http://news.bbc.co.uk/2/hi/americas/7961545.stm
please before doing this keep in mind dams have stilling basins, large chunks of concrete to slow the water flow, and waterfalls by definition have rocks at the bottom. And the water at the base of the dam does loop back into the flow, holding your boat or body at the base of the dam , looping vertically around again and again and again. Ask me how I know........
Steve