Technically, yes:
You need an active membership and cash credit on your account to pay for incoming/outgoing calls and incoming texts.
Roaming data is not supported outside of EU/UK.
In practice, many people have been having problems with roaming lately, at least in Europe, so there's a possibility that you may have problems.
As such, you might want to have a plan B...
See here for example...
https://community.48.ie/t5/Memberships/Roaming-in-UK-Wales/m-p/58051#M4724
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