Depends on where you're going.
EU roaming only works on a Guido membership.
Data only works while roaming in the EU on a Guido membership.
Nothing at all will work while roaming in the EU on any membership other than Guido.
Data is not supported while roaming anywhere else (outside EU, North America, Oceania).
It's all covered here
https://www.48months.ie/membership-plans/going-abroadHope this helps.