Welcome back, Kathleen!
Disney Cruise Line offers
onboard airline check-in service for guests who have either booked ground transportation with Disney Cruise Line or have booked their flights for the cruise through Disney. If you are working out your own flights and transportation to and from the port, you would not be able to use this service where your bags meet you at your home airport and you can check in onboard.
However, if you are anxious to check in for your flight, you could stop by the Cove Cafe the night before you disembark and use one of the computers that are available there to log into your flight reservation and check in. Keep in mind though, that there are
data fees (which are pretty high since you're at sea) and there is a small fee to use the laptops as well. If you have your own computer or wifi device, you also have the option to purchase minutes for internet access and use your own device to check in.
I'd just recommend checking in in person when you arrive at the airport, as there isn't much benefit to spending the extra money just to access the internet on the ship to check in. I know you're considering making a stop at the Walt Disney World resort when you disembark, otherwise I'd suggest simply booking Disney Cruise Line's ground transportation to make it easier to check in for your flight and send your bags ahead. But, you'll be glad to have that extra dose of Disney Magic at the resorts and park before you head to the airport.
I hope that information helps, Kathleen. Please let me know if I can help with anything else as you continue to plan your cruise aboard the Fantasy!