My dad has insisted I watch Gavin & Stacey many times but I don't like the duo of best friends as it's main characters. Little Britain is crude and just a string of catchphrases. Office and Extras, the less said about Ricky Gervais the better.
League of Gentlemen series 2 & 3 aired in 2000 and 2002. The first in was undoubtedly it's best. Spaced also debuted at the end of the 90's and Freaks & Geeks in September '99. Had to check those myself.
First series of Look Around You was fun but the second which expanded on the concept turned out abysmal.