Trust me when I say I have looked for threads that pertain to what I need and have researched and followed them extensively. I took a trip last year to Athens, Florence, and Rome, and I had spent the month before prepping my phone to work using forums on XDA. For some reason (I probably did something wrong) when I arrived at an airport in Frankfurt and tried to get my phone to connect to any networks, it wouldn't work. So I need help for my case specifically because once I'm 6,000 miles away I cannot modify my phone anymore.
I live in the US. I have a Verizon Samsung Galaxy S4, unlimited data (grandfathered), 700 minutes shared, unlimited messaging, etc. I know that the S4 works with GSM networks with a correct SIM card. I will be travelling to Ireland, Scotland, Wales, and London so I need those specific APN settings (if I need them at all.)
Thanks for reading!