The availability within your cabin to make tea or coffee varies between cruise lines, and even individual ships or itinerary. For example, P&O and Fred Olsen always provide this facility, whereas Royal Caribbean may only have it for sailings out of Southampton.
There are generally always tea and coffee stations around most ships where you can make yourself a hot drink, usually 24 hours a day. For more information we advise you to check your cruise line’s website to see what they specifically provide.