You don't need a test for a European cruise.
Water, tea, coffee and juice are available in the buffet at breakfast (typically 7-10 am, but sometimes extended to 11). Water and tea/coffee are available at lunchtime (12-2.30 or later on some port days); at snack time (4.30 - 5.30 pm); and at dinner (varies according to destination but usually 7.30 - 9 pm). There may also be a late night snack service.
Cabin service breakfast isn't free - 5 euros per person and continental breakfast only.
There is no free lobster.
You'll need to decide whether you can justify the £500 for MyDrinks. Personally I would go for it, because I like to have "real" coffee, a few cocktails, soft drinks and water and wine with dinner!