I have heard a story of a Chinese person who learnt Gaelic and then went to Ireland. No-one understood him and he couldn't understand why he was unable to communicate after all his practice! Don't know how true this is, but you can get by almost anywhere in Ireland with just English. As a foreigner no-one is going to just speak to you in Gaelic!
I don't know about Irish, but a good course for Scottish Gaelic can be found at http://topsearchesnews.com/gaelic.asp. It's the old BBC Can Seo series, videos and book.
