I have unconditional discharge, is this unspent or spent conviction? also will it effect applying NHS jobs?

Ask the citizen's Advice Bureau. CAB have free advice where the police might not want you to use their helpline for this, try the link below. CAB have solicitors who could help you with professional legal advice about this, as well as jobs advice. You could also enquire of an job agency. They'll know the legal side of things for job applications. Try Reeds or Monster, both of which advertise NHS jobs I think.