The laundry is open all day, normally there is one on each deck. There is tea and coffee making facilities in your room, also you can get a drink in the self service restaurant.
Teas and Coffees in the Plaza seemed to be available pretty much 24x7, along with chilled drinking water.
Yes, tea, coffee and water are always available in the self service servery on any P&O ship. Remember if you ask a waiter to bring it you will not only be charged for it but also 15% will be added as tips.