Hi broke down in th e outside lane of the motorway lastnight

at 1st i though the worst clutch gone, gear box blown up as I lost all power to the wheels half way through changing gears.
AA turned up and showed me two rods in the engine bay used for selecting gears that are held together by a cir clip, he tie-wraped them together, but i need a new cir clip and urgently does any one know what size I need, can i get from halfords?
cheers
Dil