I have actually taken this tour and used to host it. It's a very interesting tour. It has one of the higher guest satisfaction ratings. The best way I would suggest is to call 1-407-WDW-TOUR directly. You can book them the day of, but this will get you a guaranteed spot. It is a walking tour that is about an hour, so be prepared (you make plenty of stops along the way; you are just on your feet). If you like the LwtL boat tour, this is a more indepth version of that, and you get to ask questions at will.
Enjoy!
