Not sure if this is nation wide, but my local Cineworld is showing Heat next Monday 19th March for one day only. This will be great to see again on the big screen..
Just noticed that Pulp Fiction will be showing on 26th March, but sadly only at Cineworld Glasgow.
But their Classic Movie days are worth looking to for, usually on Mondays I believe. So far I've seen Gremlins, Its a Wonderful Life, Muppets Christmas Carol on will soon be seeing Heat.
It seems that Sheffield Cineworld (21 screens) along with Printworks in Manchester (23 screens) are about the only megaplexes in the U.K. with a sufficient number of screens to regularly show these classic movies!
Our local Showcase (12 screens) has "Event" cinema now and again.
Titanic was on recently. LOTR-FOTR is scheduled for April (hope to pop and see that one of the big screen again - fave of the trilogy). They don't do that many (and I always seem to be away when something good is on) but it's better than nothing I guess.