I have little or no heat from heater and intermittent coolant loss, no leaks, pressure test done and ok, coolant system flushed and renewed. Any help and advice would be much appreciated. 

It might be the heater control panel. Might be worth a diagnostic check 

Thanks for that, I'm thinking it's electrical myself 

Why electrical Mike?

Heater matrixes have been problematic. 
Kind regards,

Gareth. 

Hi Gareth, 

I suspect electrical as on occasion heard strange sounds from behind climate control unit just before heater stopped working and not since, also, both inlet and outlet pipes through bulkhead are hot, and with the recent flush, no sign of blockage, I would've thought that if it was the matrix, then it would have been a gradual loss of heat, not more or less instant.

Mike