Not sure about the legal issues, but you may want to check out this UK league for that information:
http://www.homepokertour.com/clubhome.php?clubid=2977
For my league, I use a tournament structure similar to the structure used for the lower buy in tournaments in our local casinos. I do this so everyone knows what to expect if they enter a casino tourney. For points, I use the reverse point system, and award additional points for people that place in the money. For example, if 10 players are in the tourney, first gets 10 points, second gets 9 points, last gets 1 point. If 3 positions are paid out, first gets an additional 3 points (for a total of 13), 2nd gets 2 points (11 total), and 3rd gets 1 point (9 total).