Twilight 2000 was a role playing game from the mid to late 'eighties published by Games Designers Workshop. It is set in a post nuclear world where World War Three happened.
Finding suitable figures is difficult, as the period (1995 - 2000) is not well covered by modern figure manufacturers.
The Soviet forces can be covered by Chechnya period Russians. British troops are more of a problem.
Crooked Dice specialise in figures for real and imaginary characters from classic television series from the period 1960-1985 One of the ranges cover the X-Commandos from the fictional series Department X. I have used them for support for A.G.E.N.T.S.
The figure below is equipped with body armour similar to that used by the British Army of the period, and is armed with an L1A1 SLR. The head supplied with the figure has a beret, so a period British Helmet would be required. Empress do a range of British helmets of the current design, one set has camouflage, which would hide any differences between the period and current helmets.