You don't NEED to learn Irish, even in the Gaeltacht in the town in which we live. English is the primary language.
However, we're enjoying learning the language. My husband's doing better than I am, mostly because he's always been a better student than I am. We live close to a Gaeltacht, have spent a week in an immersion course in the colaiste (secondary boarding school) there. Currently we're taking classes from a wonderful teacher.
We've made much more progress since we made a commitment to always say at least please and thank you in Irish, plus we start the morning with a few mintues conversation. This was his doing, not mine. I'm joining in so I'll know when he's asking me if I want a cup of tea or telling me what time it is. I've discovered this is much more meaningful than those dopey, stilted conversations one always has to memorize when learning a language.
Irish is a really hard language to learn, not for the faint of heart, but it gives you a window into the Irish soul. I'm learning Irish because I want to know how the people who raised me (elderly Irish-born grandparents) thought and why they expressed themselves in English the way they did. I believe language reflects and shapes a people's thinking.
But you definitely do NOT need to know Irish in your daily life. If you have to choose, focus on English. The Irish have carried their natural love of word play from Irish into English. People come from all over the world to learn English in Ireland because the accent is pure. Pope John 23rd's first language was Italian, but he spoke English with an Irish accent because his teacher was Irish.
People in our town are very supportive of our efforts and are happy to correct our miserable "briste Gaelige" (broken Irish).
One of the biggest problems we've had is finding a true beginner's class. Most people educated in Ireland have had Irish force fed to them for 12 years. They're nearly all convinced they can't speak a word, have forgotten everything they ever knew. Not so. The beginner's course in the immersion week was so far over our heads they had to start a new class for us. (It took them about five minutes and the teacher was excellent, a local fellow.)
It's taken us a while, but we've now found a class in the community at a true beginner level. Most of our classmates are blow ins who've married someone from the Gaeltacht. Their children attend Irish-speaking schools and they want to reinforce that. Our teacher is a lovely young local woman whose first language is Irish.
There are conversational Irish groups that meet in our local library and in a local hotel, but the biggest opportunity to practice has come from our weekly visit to the farmers' market. Most of the vendors there speak Irish, a good few of them are active in Comhaltas (a nationwide organization devoted to traditional Irish music, dance and language). There's less opportunity in the local shops, although our dear butcher has gotten over his initial alarm and joined us in the simple greetings he remembers from his school days.
One of the neatest things we've seen so far happened in the immersion course (several colaistes--colleges--around the country offer them). A young woman from Galway had won a scholarship in a radio contest. When we met the first day she assured us she didn't know a word of the language. Within three days she was chattering away in Irish like an animated magpie. It was all in there, she just didn't know it. Watching her unfold was like watching a rose blooming in time-elapsed video. People really do know more than they realize.
As usually, I've gone on way too long. Mea culpa.