If you are camping in Ireland, it is only slightly more expensive to stay in a B&B. Campsites are about €15-25, and you can get B&Bs for €30-40.
For my trip of the Republic of Ireland last summer, I bought a campsite guide: Alan Rogers Britain and Ireland Camping and Caravanning. It was very good. Lists only 4 star (lol) campsites. I emailed most of them in advance once I plotted my route, and many were fully booked at weekends, but fine during the week. I used the Irish Tourist Board website, and searched for only 4 star + campsites. That's how I got the campsites' email addresses -- from links on the Tourist Board websites. The book was useful once I got to an area and had a choice of campsites. It helped me narrow my choice.
For Fermanagh you can search the Northern Ireland Tourist Board. Fermanagh looks like Canada to me. Lots of water and trees. Very nice.
Hope you have a great time. Three months would be about perfect, I believe.
