corsa breeze 1.2 ?

the car temp gadge keeps going into the red when driving small distance or longer distance. having the heaters on in the car helps cool it a bit, the fan doesnt kick in when in the red. flushed the water and put water in, taken out air locks. found a temperature threaded bolt looking thing on a blue lead just hanging near the battery where is this ment to be? looking on the internet found out this car model has two of these threaded bolts, one in the engine and another in radiator is this correct? have checked all fuses. could it be the head gasket?