Have a feel of the hoses(watch your fingers) and see if any are cold.
If one rad hose is cold and the other is warm,it could be a blocked radiator,same applies to the water pump/heater matrix/header tank. try having a smell of the header tank coolant. usually a hint of hydrocarbon(exhaust gas) if your head gasket is fooked. a gas analyser would show it better. sometimes they're just airlocked and need ticking over with the rad cap off for a bit. check the heaters blowing hot as well. good luck.