Moving belongongs uk to ireland

Hi so after some advise and experience of people on here. I currently live in the uk and am moving to ireland in around may. Already have a house there and job sorted. I have the house from January.

I plan on moving some stuff over in a borrowed van little bit of furnature and boxes. question is what custom forms do need to fill out if getting the ferry to rosslare. Or is it easier to get the ferry to Belfast and drive down is there less paperwork that way? Any advise greatly appreciated