add noodles and carrots, then lunch will be ready when the test is overYou can test the old thermostat by putting it in a pan of water bring to the boil and it should open.
Is your rad full, is the expansion bottle at the high level mark, have you got a 50/50 coolant mix, is it good or tired old coolant change it if more than 2 years. Fan should kick in when coolant temperature nudges 4 bars. Is the Rad cap good. Check the oil filler cap for creamy deposits if there are any suspect head gasket.