We're running on the Three Ireland network so the coverage is the same as theirs.
You can check network coverage here. Choose the 'new customer' option to see the maps.
Your phone should also indicate network strength in your current location - please refer to your phone instruction manual if you are unsure where this is shown on your phone.
We've got a bunch of extremely knowledgeable people on our community, it's the best place to find more explanation and help. Give it a try