Ireland

It is more difficult to rent a car in the south and drop off in the north of vice versa than just rent in the south and drop off in the south or vice versa. Hope that makes sense.

Take the train or bus and rent in Galway. At the very least you will be looking at a sizeable one-way drop fee if you rent in Northern Ireland and drop it off in the Republic of Ireland.

If driving on the left side of the road, while steering from the right side of the car, is a concern on any level, at least a train doesn’t involve you keeping in your lane. But then, you’re on the train’s schedule and itinerary, and a car gives you more freedom regarding where and when.

Last September, we rented in Galway, drove up into N. Ireland, then back south, eventually turning in the car in Dublin. So what if you took a train from Belfast into the Republic of Ireland, then rented your car in a city there (maybe Sligo?), and then drove to Galway?