Ok, so the level in the expansion tank went down again and I will top it up after I have finished.
I removed the heater control valve and heater matrix, which was full of coolant, probably from when I first changed it.
The inlet and outlet connectors on the heater control valve literally just snapped off, I squeezed the end of the pipe with just my fingers and it all just crumbled and fell out.
I'm going to get a new heater control valve this afternoon and hopeffully that will sort out my heating problem.

The engine temperature still rises, if I drive for a while, the temperature gauge will happily sit right in the middle of the gauge.
If I stop for a few mins, the temperature starts slowly rising and then there is a point when I start to smell the coolant in side the car.

Really getting annoying.