We booked B617 as our honeymoon cruise and decided to also do B618 so friends could join us for the final two nights.
If you want to see our video, its here: https://youtu.be/xbi-HNqxKLk
We have done several short cruises before, so know what to expect from P&O but after reading the reviews for Britannia we were slightly worried, but prepared to make the most of it. I'll base this review mostly on the main cruise and will touch on the differences we noticed between B617 and B618 at the end.