These short cruises are a glorified booze cruise - expect stag nights and hen parties. It won't be like the traditional experience at all I'm afraid.
I am assuming you are reffering to the Oriana Bruges and Le Havre trip leaving in April. These short cruises attract a wider age group and you may find the ship livelier than you would on a longer cruise. Breakfast on arrival in Bruges and Le Havre can be a bit manic in the buffet as everyone wants to get ashore early. Excursions are available however shuttle buses are sometimes organised. You can take a short tram trip from the dock gate to Blankenberge in one direction or to Zeebrugge Strand in the other where you can access the railway station for the train to Bruges. The fare is 5 euros return and on arrival in Bruges it is a 15 min walk to the city centre or a short taxi ride. We spent a whole day there and it wasn't enough. Le Havre is a bit industrial and, in my opinion, not a particularly good port to walk around however picturesque Honfleur is a "must see" place and will probably be on an excursion but you can go there easily on your own steam. Check "Tripadvisor" or google "Honfleur" for current transport arrangements. You may find the ship is pretty busy as everyone wants to do as much and see as much as they can during their short time aboard so service may be a little slower than you would normally expect but it should still be an enjoyable cruise. Smart casual dress code although dress up if you wish but there is no expectations for posh frocks and DJ's . Hope this helps.
We went on a three day cruise on Oriana last year. We really enjoyed it. We did not find it to be a glorified booze cruise. I'm afraid I disagree with Rum Runner in that the majority of people did really dress up on the Formal evening. We were on a table for 8 and all the men had DJs on. We would not go on a 2 night weekend cruise but we found that the 3 nights really gave us a good break. We went to Rotterdam and Zeebrugge and decided on the day that we docked in Rotterdam to stay on the ship and explore what she had to offer. Oriana is a lovely ship and we have since spent a week on her in the Fjords. I'm sure you will enjoy her. Do take some formal clothes with you, I wouldn't want you to feel out of it on the formal evening. Enjoy your trip.
I honestly didn't realise there was a formal night on P&Os short cruises. I have only done the 2 nighters. We live and learn. And for Goddard of Westbury, I am told a taxi to Honfleur from Le Havre and return can be done for 30 euros.(2007 prices).