Just an update gents. Got back from holiday and pulled the glow plugs out, turned the key and it was like Niagra falls. Absolutely ****ing water. So I drained it of all coolant and turned it over, once the water cleared it started no problem. So I set about pulling the cylinder head off. I found it very easy and logical. Didn't need to reference the manual much. Pulled everything apart, changed head gasket, transposed all gubbings over to new/ refurb cylinder head and refitted in around 6 hours. Once old head is sent away and pressure tested I will truly know what the culprit part was. But decided to change them both at the same time to save time stripping and rebuilding if the gasket wasn't at fault. She fired up straight away and is running sweet again now. Thats 2/3 months of ownership out of the way and I've changed a prob, a slave cylinder and now cylinder head and gasket. The experience is building fast. Thanks for everyone's input who helped with my questions initially, much appreciated