Our first European cruise was the 12 night British Isles. I was very nervous about the excursions because this was our first time in Europe and we were only Gold. So I thought that by the time I was able to book, it would be sold out. Fortunately, that wasn't the case, but I did book at exactly 105 days prior and was able to get the ones I wanted.
I was a bit overwhelmed with the planning and learning everything about travelling and visiting UK, that I believed that I should book everything with
DCL. Within a month or two, I cancelled a couple and decided to visit the town ourselves which we were glad we did.
I do feel that if we had a long time at port, I would choose to do a private excursion. However, not being familiar, we were hesitant. With our upcoming Norway/Iceland cruise, we are also doing some DCL excursion, but not to the extend of our British Isles Cruise.
As a background, we rarely booked DCL or any excursions when we went to the Caribbean. We spent most of the time in town. After several Caribbean/Bahamian cruises, we had booked only 2 DCL excursion...one was (on one of our earlier cruises) in St. Thomas and the other one in Cozumel. Our excursion in Cozumel was amazing and we were very glad to have done it....the one in St. Thomas...no so much.
For us, I would be more interested in doing excursions (vs going into town) in Europe than Caribbean.