This isn't very relevant to your situation (unless you're open to going somewhere other than the UK/ Ireland), but I'm a big fan of cruise vacations in general (and especially on honeymoons). You don't have to worry about hotels, rental cars, or restaurants. Minimal stress/ planning, but tons of options.
Without even leaving the ship, you can: (1) lie out by the pool and read; (2) drink yourself stupid in relative safety; (3) dance; (4) gamble; (5) stuff your face with gourmet food at all hours of the night; (6) or stay in your cabin and explore the joys of marital congress.
If you're feeling adventurous, get off the ship and spend the day exploring, para-sailing, whatever. But if you're not feeling it, you can always wait for the next port. My wife and I spent 3 days on Maui before doing a week-long cruise of the islands for our honeymoon, and it was amazing. Looking forward to cruising the Grecian isles for our 10-year-anniversary.