The travel to Eire might be the problem, depending on the airline or ferry company you use, and some form of established ID might be required. If you are a UK citizen and resident then travel between 'the border' is relatively simple.
One difference to the rule is if you arrive on your own yacht, then the formalities on arrival and exit are required.
Well I would not trust it. photo card driving licence may be Ok but I would enquire first. I was going to go in the summer and thought cheaper to upgrade my driving licence with a photo than getting a passport and on further enquiries I needed a passport. So went to sunny scotland for 10 days instead and it rained for 9 of them.