Entering M50 at Sandyford.Before I suggest an answer, can I ask where in Dublin are you travelling from ?
No traffic if heading east at Dunkettle from M8, with the new free-flow system, then take dual carrigeway all the way to Midleton, faster, safer, turnoff for Ballycotton at final dual carriageway roundabout.M9 down to Waterford, through Dungarvan and Youghal and turn left at Castlemartyr Bridge. Only 1 toll on that route, and whilst you do run the risk of getting delayed on the N25, the other way you run the risk of getting delayed by traffic heading to the tunnel if anything happens there. Also if you go M8 and if you turn at Lakeview Roundabout at Midleton, the road from Cloyne through Shanagarry and onto Ballycotton is pretty awful. Alternatively, if you come keep going past Midleton to Castlemartyr Bridge, the traffic coming into Castemartyr from that side is way worse usually then if you come from the Youghal side.
You have three possible routes:Entering M50 at Sandyford.
No negotiating of dunkettle, its free flow, no back up at all of traffic heading M8 EAST to Midleton.PS Castlemartyr traffic is only bad at the usual school and rush hour times - no problem outside of those.
But having to negotiate Dunkettle at the end of a drive from Dublin would be hellish.
Much easier to come via Youghal, relax with a beautiful coastal view for a few minutes and then on to Castlemartyr, turn left at the only crossing there and drive straight down via Ladysbridge to Ballycotton.
Enjoy.