Petrol stations in Ireland are self-service.
Will it be possible to find somewhere where the service is offered? Probably.
Anecdotally I haven't been anywhere that does that in the last 20 years (and it was very rare then).
Even then the situation you're describing is quite different. In places like New Jersey, AFAIK it's required that an employee operate the pump while when serviced stations existed in Ireland it was an offered service rather than a required one.
Fill your tank then go into the shop to pay (park away from the pump first if you're especially polite).
Prepay may be required in some 24hr stations after a certain time (eg. midnight), though even then it's not very common. Where this exists, it's normally either prepay with card at the pump or at a service window at the shop. Very, very occasionally a station will have one of their pumps which is prepay 24hrs (with other pumps working as normal).