Ok, all on lovely, timed up mint levered down on the tensioner arm as you said and it's clicked up a few clicks and is now sitting about 5mm above the surface but the chain is still slack accross the cams, if i lever the tensioner arm upwards about 2mm it pulls the inlet cam round so that the slack is gone and the marks line up with the head.

I've span it over on the starter in the hope oil pressure will push it out that bit more but it's not happening at starter motor speeds anyway.

Is this normal? will it fill with oil and jack out fully when oil pressure is higher than starter motor speed?