Not sure if this will help or hinder but I've travelled around the island of Ireland twice by motorcycle, once with the wife and once with my son; on neither occasion have I found it necessary to book accommodation in advance as there is so much choice it's just not necessary. Unless you've something specific to aim for in a particular place then just breeze along until you fancy a stop, there will always be somewhere to lay your head, from the smallest B&B to the grandest hotel. If your first choice is full then ask them for a recommendation, you won't be disappointed.