PPS: Drive from Dublin ferry used to be about 2 hours, but with more traffic (though better roads) it could now take longer these days. It also depends on the time of day: you really do want to avoid the morning & evening rush-hours. You should be OK if you allow between 2 & 3 hours - I haven't driven that run in years, as I now live in the far south, but the traffic in Dublin is FIERCE, so bypass the city centre and keep on the main through route heading west. Longford is right on it.