It's all sorted - thanks to Breezer for taking the time to type....but...
It was my header tank (the little one) - due to the extremely warm summer my ball shaped object attached to a bar of metal (sorry but the name escapes me) had stuck in the up position, thus not allowing any water to go...
I myself am a technical numptie and have the following question:
Heating is working fine but this morning I have absolutely no hot water.
Could this be a simple problem I can sort myself or do I need expert help and re-mortgage the house ?
Cheers anyone that can help.............