Settle on the dates for your trip. Planning ahead often allows you to avail of specially priced travel deals. The more flexible you are in terms of travel dates, the more options you'll have.
Book a ferry for your chosen date. Ferries are booked via company websites like Irish Ferries. Choose the route from Ireland to France and select the month, day and preferred time of travel. Travel from Rosslare in Ireland to Roscof in France is an option, for example. If returning to Ireland later, include the return information as well. Add the number of travelers and get the available information for rates.
Remember to take into account the fact that rates are variable depending on the time of year, the availability of tickets, whether transportation is needed to get to the ferry and whether travel is round trip or one-way. A typical ferry ride between Ireland and France, without factoring in transportation to get to the point of embarkation, costs around $150 dollars per person on average (as of 2011).
Select the preferred trip from among the options and rates available. Pay the fees and costs when required and print out the confirmation information. The trip from Ireland to France is usually around 20 hours, with some variation depending on the specific starting point and final destination.