Pick from this list, you can't go wrong with:
Guy Gilpatric and his Glencannon series
Ernest Bramah and his Kai Lung stories
William Hazlett Upson and the indefatigable Alexander Botts
Three men in a boat and Three men on the bummell by Jerome K. Jerome
The Diary of a Nobody - George and Weedon Grossmith
Sue Townsend's Adrian Mole series
Mark Twain's Innocents Abroad
Anything by David Sedaris
Charles Dickens' The Pickwick Papers (read the unabbreviated version)
George Ade's Fables series
Douglas Jerrold's Mrs. Caudle's Curtain Lectures
Saki's Reginald
James Thurber's short stories
Leo Rosten's Hyman Kaplan stories
E.M. Delafield's Provincial Lady
Joyce Dennys' Henrietta
Anything by Gerald Durrell, but especially the Corfu trilogy
Yes, Minister and Yes, Prime Minister by Jonathan Lynn and Antony Jay
Most anything by P.G. Wodehouse
Any of Bill Bryson's travel books or his autobiography
As you can gather from the above list, i'm a fan of British humor. Don't make me choose among these...please.