PAL is the colour system used on UK TVs.
NTSC is the colour system used on American TVs. Most up to date UK TVs will accept an NTSC signal, so you should be able to play Wii Sports. However, you will need a stepdown converter which reduces the UK voltage from 240V to 110V and allows the American plug to plug into it.
Also, bear in mind that the NTSC console won't play PAL games without some kind of converter like a Freeloader, which hasn't even been confirmed for release yet.
You're better off getting a PAL Wii to be honest.