Big Kids is a 13-episode comedy series that premiered on CBBC on BBC One on September 27th, 2000. Noggin signed on to create an US localization. Noggin was only credited in the US edits of the episodes, and the series' copyright belongs solely to the BBC.
Big Kids aired its thirteenth and final episode on December 20th, 2000. It premiered on Noggin in the United States on January 29th, 2001. The series also ran briefly on Nickelodeon from March 9th to March 25th, 2001. The last time it aired on BBC was in 2009.
Keep in mind that there are two versions of the show: the original UK one and the US localization. I think the US version would be harder to find, as it aired on Noggin's "The Hubbub" block in 2001, which is also mostly lost.