Hi Darcy and welcome to Slow Travel,
Our family did a week-long walk on the Kerry Way in early July a few summers ago. We did a self-guided walk, where our arrangements were made for us and our luggage was moved every day. Our walk began and ended in Killarney, which is a very popular tourist destination and was packed with a Harley convention on our first night. We would not have found a place to stay if the walking tour company hadn't arranged it in advance.
I don't know about the route of the Dingle WAY, but part of the Kerry way was through very isolated countryside. We stayed several nights in small home-type B&Bs with just a few rooms that were off on their own-- not in a town. If we had arrived to find they were full, it could have been miles to another place.
I really think that for July you need to make your arrangements in advance. (If you are in isolated places, you may also have to arrange your dinner at the B&B.) Do a little research and you'll have a sense of which towns/villages you want to linger in. Another benefit of this is that you won't have to worry about accommodations-- you'll have a specific destination each day with no decisions like that to make.
One other suggestion-- the weather was extremely variable during our week in Ireland that July. We hiked in shorts a few days but also in full raingear and fleece jackets on other days. We have also done long distance hikes in England in July. Be sure to have good raingear-- especially good rainpants and a cover for your pack.
We have done five long-distance walking trips in Europe-- getting ready for #6 this summer in France. It's a great way to experience Europe and such wonderful exercise too.
Some earlier message board threads on hiking in Ireland:
Walking trip in Ireland? Hiking the Dingle WayKathy
