Her first major television role was in 1997 when she was cast as Zoe Gerrard, a security officer in the medical drama Casualty. In 1998, she joined the cast of Comedy Nation, a satirical Sketch show that featured some of Britain's leading up-and-coming comedians, such as Sacha Baron Cohen, Julian Barratt, and Robert Webb. This was followed by an assortment of parts in various television productions, including a performance in a two-part story for the police serial The Bill in 2000. That year Oberman was cast as series regular "Beverly Jordan" opposite Michael Barrymore in Bob Martin, and became a lead performer in the award-nominated Lenny Henry in Pieces, starring actor/comedian Lenny Henry, which ran until 2003. In 2002 Oberman joined the second and final series of the Sketch show Big Train, performing beside comedians Simon Pegg and Catherine Tate. The following year saw the Harringham Harker move from radio to television as part of BBC 2's Autumn line-up alongside The Office and Coupling, with Oberman continuing in her role as lead and Writer.