It's been a few years since we sailed
DCL in Europe, but each time we stayed in a hotel booked through Disney where a lot of other people were also staying. They had a check-in desk either in the lobby (Barcelona) or in a meeting room (Barcelona - different time - and London) - open only a few hours a day a day or two before the cruise - and we were given a selection of times for the transportation. We got immediate boarding when we got there and checked in so no PAT required. You might have to check with the front desk to find out where the DCL check-in desk might be. We had a problem finding it in our hotel in London because we weren't given instructions, so if you don't hear anything or know where to go, definitely go hunting for it.