I don't know if this is relevant but when I open up the Automatic Air
Vent bleed nothing comes out no water or air.

It may well be relevent. Are you sure you've topped up the system to enough
pressure? What does the pressure gauge read when cold? It should normally be
at about 1-1.5 bar. If not, top it up until it is. Then fire up the boiler
and wait a few minutes. If the pressure goes about 2-2.5 bar, then you have
an inadequete or broken pressure vessel. If the cold pressure steadily goes
down in less time than several months, then you have a leak or dodgy
pressure relief valve.

Christian.