i'm thinking this might be a clutch master/slave cylinder thing, but i dont know where the resoviors are. (i think i know, but it may be the brake one)
The Master Cylinder reservoir is next to the Brake Master Cylinder.Bolted to the firewall, directly in front of the dteering wheel.Pop the bonnet and have a look.
And I think you might be right about it being a fluid problem.
It could be either the Master Cylinder or the slave cylinder(bolted to gearbox,near radiator) or both.