The drinks package is worth it if you drink 6-8 drinks a day, which we can do easily. The cheapest alcohol package is now £41 pp pd but the drinks prices are very reasonable so if you wont drink that much then its not worth it.
Depending on which package you choose then you either go to dinner at a set time (club dining - 630 or 830) or any time between 6-930/10 (freedom dining). I think you pay a bit more for the freedom package but for us its worth it.
If you want the sort of excursion that is a guided tour of the port town you are in, then they usually have local minicab firms, land trains, buses etc that will do them for a much better price then the ships excursions. We have never bothered with the ships ones and either walked round ourselves or used the local ones.
On the last p and o cruise we did, we felt the quality and choice in the buffet was less than previous cruises, but there is still plenty of food.
The Internet package is silly money so we didnt bother. As my network (vodafone) doesnt connect to the maritime date network, i just left roaming on and paid Vodafone £10 for a weeks roaming bundle. It doesnt work at sea, but its nice having yes break. Even teenage DCs wasnt too bothered about it.
If you type in your cruise code into facebook, there will be a specific group for people going on your cruise, if you wanted to chat to people before and ask specific questions or just get hints and tips.
We only discovered cruising the year before lock down, but have just come back from our 5th now, we love it. I hope you have a great time!