[rrobson]

unfortunatly, i would have to agree with t-cut. after experiencing hgf myself, these are the exact scenarios i was faced with.

if it is hgf, water is being pushed out because the cooling system is being pressurised by the exhaust gasses entering the cooling system through the headgasket, as tc said.

there is a little saving grace that is as long as there is plenty of water in the system, and you dont let it overheat, you will be fine to run it (short distances anyway)
with mine, i drove it 60 miles home, and circa 50 miles a day for a full week before it finally went in for repair. it needed about a litre every 10-15 miles, so i just put 2 litres in every time i set off home.