2005 golf plus 2.0tdi. First losing coolant rapidly, no overheating. Changed water pump, had to do all belts to do so £500 gone. Changed housing gasket on the side of the head £90 gone. Now when driving at normal 30mph temp stills normal at 90° if put under pressure temp will rise, sometimes to 120° but no warning lights come on but coolant reservoir will throw coolant out the top. Fans are working. I'm guessing its one of two problems either Thermostat or head gasket but I'm hoping its not the latter. Any advise or opinions would be appreciated as I'm losing my patience and heading towards an early grave lol.
