Ooooh, steady.
Depends on the DVD and TV combination that you have - and part of that will depend on where you bought the stuff.
I've purchased three multi region dvd players - and three multi region VCR's - whilst out here in Florida.
Check the specifications carefully. It's quite possible that the DVD player will PLAY any region of disc - Region 1, region 2....PAl or NTSC - quite happily but will only OUTPUT the signal in EITHER PAL or NTSC (or even SECAM - as I said, depends where you bought it).
Now a modern British telly will, quite likely, accept an NTSC signal and convert it for you to let you see it on in PAL (so your video tapes should be the right length).
Read the manuals before you dive in too far.