I think the DS AC adapters are not multivoltage so you shouldn't plug the in different countries. UK has 240V so you would blow up an american one, which should work at 120V.
Of course, you can use the AC adaptor of the region you physically are, no matter where your DS is from. Or just use a step-down adaptor and your original charger.
another question off topic, does the ds lite come with like a screen protector already over it? cause mine has had this wierd bubble thing in it since i got it in the bottom touch screen.
wonder what the wierd bubble thing is then :S i got mine new too, got it just like a couple of days ago to keep me occupied during my flight and stop over.