Hi Craig,
Cork is indeed a super place to visit and I'm glad that you enjoyed yourself so much that you are coming back in August for four weeks!
While you are not looking for an organised tour, they are wonderful sources of information and have many routes and suggestions on their websites.
With regard to a coastal path from Rosslare to Cork, there isn't a complete path but several small and loop walks.
County Cork itself, as part of the
Wild Atlantic Way, has plenty of coastal and slightly inland routes to keep you busy. We have a super search page of
Cork Walks that will be a great place to start your plans. There are a couple of coastal walks, Seven Heads Walk as I mentioned before and
Allihies Copper Mine Trail, a fantastic walk out along the Bear Peninsula.
I hope that this helps and I'm sure our community members would be happy to chip in and help with your planning also.
Martin