There is one launderette on all cabin decks which is free to use but you must supply your own soap powder (available to buy in one of the shops).
Yes there is a laundry service they also have washing machines and dryers and ironing facilities on each deck .
The dry cleaning service on board is normally first class and priced better than the high street. I will often have things dry cleaned, like my tuxedo, at the beginning or at the end of a cruise depending on time .....Nei.
Use laundry 1st thing or late at night when its quiet. prior to evening dinner very busy!