Had the car 4 months seams to get to temperature on gauge slow compared to my mk 2 1.6 petrol 

drove 22 miles other evening noticed temperature gauge was sitting at half way to 1/4 mark 

drove it next day to see if problem was still there , it went up to between 1/4 & centre lagged a bit then went to middle then it was fine 

drove it to work all week only 4 miles each way seemed normal but only gets to a 1/4 with short journey 

Friday went out -2 same again sitting between below 1/4  , went back out after about 6 miles it finally went to normal so I decided to put heat blowers on for about 5 seconds turned off & the temperature gauge dropped back down between under a 1/4 in seconds & stayed 

got back home had to nip out again about a hour later temperature gauge went to normal centre  so tried blowers fine stayed at centre 

Any  ideas anyone else come across this ,  my coolant level is about on minimum , could this cause air to get in or maybe a intermittent sensor/ thermostat 

thank in advance 

If the temperature is jumping about so erratically my first guess would be the sensor is on its way out, I had a similar issue on the missus' Beetle recently and it was the sensor.

No , just them two blips , both times it was cold-1 /-2 , could well be a sensor because I’m thinking it would be playing up more often than not if it was the thermostat ,