So your car has no props and the IRD has been disconnected from the cooling system.
And you think putting props on it will make it 4WD again?
I think you're hoping there. Sounds like this car has had some "issues" in the past which is why its now running 2WD.
You might be lucky, but looking less likely as more info comes to light.
At least as you only paid £175 for it, you have money left over for props, VCU, support bearings, IRD & diff!
When you get the props - make sure you get the nuts and bolts for it. You'll need the one to connect to the rear diff, ones for connecting to the IRD pinion (together with the plates they go through) and the 4 bolts for the VCU support bearings.