The episode is set in 1997, and the characters in this episode are mentioning watching Ally McBeal and Knots Landing: Back To The Cul-De-Sac. However, Ally McBeal was not screened in the UK until mid-1998, and Knots Landing: BTTCDS was not screened until 2001.
The Posh Spice doll from Tameka's bum-bag and the one found by Hayley are both 1998 editions with short hair. Incidentally, Simon mentions he wants the "fabulous tour outfits" to go with the doll; these were also not produced until a year later as the Spice Girls did not tour until mid-1998.