I used to play one double session every other Sunday (I think) at Royston. Used to love it but don't get to play now. Used to be quite cheap too for 40mins thats why we were happy to play a double session.
Used to go to Metrodome once a week Double session, got quite good and then my dad slipped a disk in his back and we stopped. Would like to get back into it though
My dad was a member at the gym so we got free off peak sessions I think peak times were around a fiver for a 40 minute session.