i may be working in the Eu soon going from n.Ireland to Belgium and TheNetherlands and back can anyone tell me if I need a passport for this or not…thanks people.
Yes. (Unless you are wearing storm trooper kit and invading them countries that is)
assuming the op post is real.(it cant be surley)■■? then remember and get it stamped in Dublin 1st just to be on the safe side. and on your way back to be an ambassador for your country and give a few hitchikers a lift if your bored and needing a bit of company.theres usually a few to be seen around Calais docks with their thumbs up. 
Euros with ID cards don’t for travel within the EU, but we don’t have those in UK & thus need passport.
I see you put NI, so part of UK, but has ire got ID cards yet? If so & you got one, then no, don’t need passport.