America have a different power system than us, it's 110v 60 Hz and ours is 230v 50 Hz. I think this is why TVs have to have a different video system. NTSC works at 29.9 fps at 60 Hz and PAL works at 25 fps at 50 Hz. These differences mean that an American video will still play on our machines, just not properly (black & white video and it will play slightly faster than it should). That's why when an American TV show is shown over here, the sound is slightly faster and the colour is a bit more dull.
If you have an NTSC video recorder, you'll have to have a TV that can display an NTSC picture (unless the video recorder automatically converts to PAL). So it's easier to go on jimv7's link and find a UK-based video shop that will send out PAL tapes.