If you are talking about FTA satellite the following are the main channels available
BBC1, 2, 3, 4, NEWS24, CBBC, CBEEBIES
ITV1, 2, 2+1, 3, 3+1, 4, CITV
SKY NEWS, BLOOMBERG, CNN, EURONEWS and a couple of other news channels
FILM 4, FILM 4+1 and various other movie channels
Several music channels including Bubble Hits
The channels listed above are the most well known and popular. There is also a large number of shopping channels, gaming channels, religious channels and dating channels etc.
The above are found on the same satellites as the sky channels so if you have a sky dish in your house already you could purchase a FTA receiver.
Other satellites contain FTA channels also but most dishes in Ireland point at the satellites sky use.