We have a placeholder for the July 30 11-night Iceland cruise in 2021. Ports include UK, Scotland, Iceland, Norway, Copenhagen.
We've toyed with pushing back to September and doubling up between the British Isles route and Norway route.
I haven't done the British Isles specifically but I have done two(3 if you count Dover) of the ports on a WBTA.
We treated Embarkation day as a Port Day in Dover. We came down from London the night before and stayed in Dover and got up bright and early to tour Dover Castle. If you haven't seen Dover Castle, and you have interest in either Castles, Medieval history or WWII history, it's a must. It was AMAZING. If you get there when it opens and plan well and don't take breaks you can see it all in about 3 hours and then head to the Port and get onboard the ship around 2:00pm. If we had more time we would have just relaxed our speed seeing the sites more, but we didn't skip anything inside Dover Castle either.
Dover has several other things we want to do, including a hike along the cliffs, the Dover museum, the Roman Painted house, and the WWII Gun bunkers and such along the coast. We can't wait to get back. Lots of people say "don't stay in Dover, Canterbury is nicer" but for a one night stay before Embarkation on a ship it worked great and allowed us to be there early and have basically a full day of "Port Adventuring" on our own before we even started our cruise.
We really enjoyed our time in Portland England. We booked a PA through
DCL because we wanted to do something specific they offer that you can't do on your own. They booked a private tour of a manor house and cream tea, which is not open to the general public for tours. The Minterne Manor House gardens are open to the public, but it doesn't offer general tours inside the home. This was AMAZING. If you enjoy old manor houses, this was WELL worth the time and money. You were basically allowed free reign over the first floor as a guest. You are encouraged by the Lord to walk around, sit on the furniture and take in the house. It felt like someone let us step into a BBC program for an afternoon. I know most people go see Stonehenge in Portland, but if your not interested in seeing stones in a circle, this PA was great. We talk about it fondly often.
Our cruise went to Ringsakiddy Ireland (which is the industrial side of Cobh and a royal pain if your ship goes to that port) but since we knew this ahead of time we booked a private guide for the day to get us to Midleton and Cobh. Your cruise looks like it is going directly to Cobh, and this is an AMAZING port to dock in. The ship pulls up directly alongside the main downtown street. You are steps, in the most literal sense, from shopping, dining, and the Titanic Museum. It's easy enough to then get to Midleton for the Jameson Distillery as well. Cobh was great. With our guide we did a ton of stuff, all of which we loved, and only spent about 90 minutes on Cobh, and wish we had more time there. It's a great town.
I hope that information helps you make your decision. Whatever you do it will be great fun.