The UCI chain will be selling tickets for Fellowship of the Ring as of Monday 19th November. It's stated at the bottom of their film times leaflet that can be picked up at any UCI cinema. I would assume that this is for opening day on 19/12.
For those Brits who haven't seen the newest trailer in all it's glory - ensure that you're in early for Harry Potter - the trailer is in front of Harry Potter (which I saw at the weekend). Harry was a very, very good film - one of the best of the year but the trailer was mindblowing! Whether the trailer for Episode II will supersede it (IF we Brits get it;)) remains to be seen.