Carnival Has a transfer service from Orlando airport to Port Canaveral. You can still purchase transfers in advance or at the airport, regardless if you purchased your air thru Carnival, or on your own. Transfers are 30.00 round trip or 15.00 each way.
Carnival representatives are at Orlando airport starting around 10am. Just ask any airport employee to point you in the right direction.
Hope this helps,
We'd suggest that you take the Bee Line Expressway and not the Turnpike if you plan to make your cruise on time :o). When you come out of MCO, just head east on bhe Bee Line Expressway (SR 528), and within 45 minutes you'll see Port Canaveral off on the left. You will exit SR528 to the right and loop around, so stay in the right lane, and you'll be fine.
Have a great trip to FL, and Bon Voyage.