OK, ****UPDATE NO 3****

Though't i'd check all my levels this morning.... no fooking water in the header tank again Tiny bit at the bottom, so some still in the system. Fill her up this morning, drive the 20 odd miles to work, car is running as normal and not getting hot (Still have no thermostat, btw ) get to work, it is empty again Fill it back up, start it, looking everywhere for a leak, cant see where it could be leaking don't seem to be round the thermo housing, nothin visible from any of the pipes or anything, there is no great puddle on the floor under the rad so im confused, where is all the water going so quickly then

Help?