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Is that Oceana the ship or Oceana the Cruse line ?
If its P&Os Oceana then most of it is free cafe Jardin has a charge for diner as does the Horizon Grill...Taffy.
If it's Oceania then all are except for the select dining room. There may be a restriction on the number of visits to the Speciality ones.
I assume its P&O Oceana, in that case included in your fare are the main & self service restaurants for breakfast, lunch, afternoon tea, dinner and late night snacks. Also Cafe Jardin except during evening when there is a chargeable menu. If you mean by inclusive, alcoholic drinks are not included, nor are your tips which are £3.50 per person per day. Tea, coffee and biscuits are provided in your cabin. For a full list see p&O website.......https://ask.pocruises.com/help/PO/before-you-sail/fare_included..........Brian.