This post got lost in the Readers Cruising Grounds section. So I've moved it to General leaving a ghost topic behind.
BB do you mean Wiremill Ski Club? It's just down the road from me and they only allow club boats and skiing, no wakeboards or toys. A small friendly club with a rather nice pub attached to the lake.
Nick, most lakes in the UK are either private Ski clubs with their own boats run on LPG or fishing club lakes. Scotland seems to be the last bastion of fresh water sportsboating. Not much help I know.
When we lived in Marlow, Westhorpe Farm (known as Westhorpe Water Sports) used to let members use their own boats, not sure if they do now. You would have to join the club then rent the lake by the hour, quite expensive.