Ireland is an island and there are no tunnels or bridges (or any other means) that would be suitable for cars, buses or trains.
Sorry, the only practical way to get to Ireland is a ferry or airplane ride. Both are relatively short: the plane ride is about an hour and the fastest ferry from Holyhead to Dublin takes about two hours.
You will have to choose between visiting this beautiful island and some travel inconvenience. Keep in mind; it's only a relatively short trip (from England) and many thousands of people do travel to Ireland every single day without any problems.