Best way to avoid roaming in Ireland and Scotland

My wife and I have two lines on Essentials, both using iPhone 14s. We'll be in Ireland and Scotland for about ten days and would like to avoid ANY roaming charges, but would still like to use our phones on wifi and text messaging. T-Mobile chat support seemed to say that texting (assuming just SMS?) is free internationally, but it’s not totally clear to me.

I’m aware of the two blocking options available per line in settings (Bloqueo de roaming internacional con cargo y Bloqueo de roaming internacional (incluido roaming internacional con cargo)), both of which are a little on the confusing side; one chat agent said to use the first, the other said use the second. Huh? 

Which should be used to block incoming calls & voicemails but leave texting available?

As far as voice calls, I'm assuming that forwarding both lines to Google Voice will allow for voicemails to be left for us without roaming. Is this correct?

Would appreciate any other suggestions beyond what I’ve asked above!