The landscape for getting B&B rooms these days has dramatically changed, making it much more difficult and competitive than in the past. The reasons: temporary and permanent closures due to Covid, retirement and ageing out; conversion of some traditional B&Bs into AirBnBs; 30,000 Ukrainian refugees being housed in hotels and some B&Bs; and perhaps most noticeably, the dominance today of the Internet, which makes booking rooms many months in advance easier than ever before.
I've bicycled all over Ireland many times over the years, though not since 2007 when there were about 2,500 B&Bs in the Republic and the North, all of which were published in the annual B&B Guidebook put out by the Irish Tourist Board. We'd show up in whatever town we chose to stay in that night, knock on a couple of doors or make a phone call or two from the ubiquitous phone booths and have a room within minutes. Not so anymore and maybe never again. Based on the multiple resources I used in planning this summer's trip, there may be only about 1,000 B&Bs operating in Ireland today. The print version of the most recent B&B Guidebook lists about 700.
To be on the safe side for my month-long bike trip this July and August, I took the hints (above) from contacts there and reserved rooms for every night. It took a full month this spring and hours on the computer each day to send and receive hundreds of e-mails, plus make a few phone calls, to nearly every B&B I could find along my route. About one-third never replied. But I now have a place to sleep every night in my desired towns and villages around the coastal perimeter of the island.
Keep plugging away though and ask for referrals to other B&Bs if your first choices are full. I had a few successes doing just that.