Ok, I am sure no one here has done the whole 387 miles. Has anyone done part of this hike it starts in Dublin and goes to the south west coast.RR

With Ireland it depends on the weather. Regardless of time of year, you might have bright sunshine or it might rain hard everyday.

I have driven it. Roads but few places to walk apart from towns. You need to seriously plan and book accommodation ahead.

Robert - I have done bits of this and it seems now that you may have a clear route from Dublin to the Midlands all along the canal so no need to walk on roads. The bits I have done by foot and on horseback (through Meath and Westmeath, where I used to live) have been rough track but no doubt there is a mixture of tarmac, track and just grass along the route. This may not be the the route you were thinking of, though, as this goes West from Dublin, and slightly north, not South West. Perhaps you are considering a walk along the Grand Canal which goes through lovely countryside although if you get tired it would be more difficult to pick up transport along this route.