On P&O ships the evening's dress code applies to all of the ship.
It's great fun dressing up on formal nights-if you don't want this why not try an ''informal;; ship.
It is generally accepted that if the man wears a tie and has long trousers on , that is acceptable . Though I have noticed that a tie is not always mandatory in some of the eating areas. Also a dark suit will surfice if the man does not have a "Dinner jacket" if you want to eat in the main restaurant.
I sailed on P&O ship Arcadia last year and will also be sailing on Oceana in September this year. P&O have three types of dress in the main dining room, formal, semi formal and casual. On the cruise I will be on in September there are 3 formal nights when most men wear suites and bow tie, three semi formal nights where jacket and ties are worn and casual nights for open neck shirts and trousers. Part of the enjoyment of cruising is to dress up, men in their suites, women in their cocktail dresses and very elegant they look too. Don't worry I'm sure you will have a great time.
We cruisd on oceana two years ago in the caribbean and the dress was smart casual except on formal nights where you would look out of place if you didnt have either a DJ or lounge suit o.
Freedom dining works the same as fixed dress codes the same in a 15 night cruise we had 4 formal nights when a dark suit or tux was needed the rest trousers and a open neck shirt are fine enjo.
Freedom dining means that you are not restricted to the same table and eating time each night, that way if you dislike someone you've been seated with you know that you're not stuck with them for the rest of the cruise.
We were on Oceana Transatlantic in March we did the freedom dining and found it wonderful, if you dont like dressing up on formal evenings just go to the Bistro (small service charge) or even the Plaza buffet which we found very good otherwise just go Ligurian rest. during the daytime and book yourself in for that evening - fantastic - you meet diff. people everynight and you can go in open necked shirts with smart trousers. Just go and enjoy it as we did.
On your question about freedom dining, don't do it, we went on a mini cruise in april on the oceana and had the freedom dining, only to be told you could only have selected times which turned out to be not very good at all and some people could not even get into the restaurant if they had'nt booked, so next day went early in morning to book for that night only to be told that there was only 6.30 time slot left, a bit early for us as we would be out off the ship all day, but had to take it, my advice to anyone thinking on freedom dining is it's not what it seems.we will be sticking to set sitting dining in future.
On formal nights it is not compulsory to dress in dinner suit, lounge suit will suffice. However the majority wear formal dinner clothes on formal nights!
Firstly freedom dining you can just turn up at the restraunt but during busy periods you may need to wait for table normally only 15-20 mins or you can book in advance for the time you want to dine at. On formal evenings you Husband must wear at the very least a suit and tie as the dress code applies to the whole ship no matter your choice of dining. All other evenings no tie is required but a jacket is on informal evenings . Hope this is of help to you but dont worry too much about the dress code they will tell you what you need when they send out your cruise inf.