OP region coding and pal/NTSC output are two different things.
The Region coding determines what market the disc is designed to be playable in, with Region 1 being the US and Canada and Region 2 being Europe and Japan. As you may know Japan also uses Region 1 coding, but their discs are NTSC. Region 0 means it is designed to be playable Worldwide. This is a separate issue from the disc being NTSC.
If the DVD is Region 0 NTSC then your DVD player will happily play it, but will output (normally) an NTSC signal instead of a PAL signal. Some DVD players can output what is known as Pal/60, basically a PAL signal but at 60Hz instead of a standard PAL/50 signal from NTSC DVDs, one or two can even convert to a standard Pal/50 signal which any UK TV will display while most modern DVD players will just output the NTSC signal from the disc. Some TVs not designed to accept NTSC can display a Pal/60 signal. However, pretty much every TV in the last 5 or 10 years will happily accept an NTSC signal, but sometimes only via one of the scart sockets. Best bet is to check your TV's manual.
So if the disc is Region 0 your DVD player will recognise and play it.
If your TV accepts an NTSC signal, it will happily display a picture but if it doesn't, it may accept Pal/60 if the DVD player can output it.