Goody, hold still, you are hopping all around in that corner
You will need to fly or water taxi to mainland.
You should take a day or two overnight, to really experience it on the mainland. One hit and run isn't going to give you the real feel.
Many people do a 'surf and turf' in Belize.
Taste the land and taste the waters.
How you do it from AC is not something I have never done. We do it the other way around.
Wildlife, go to the Zoo. It's not your typical zoo, the animals are in fenced areas and it's the only way you will actually see them in Belize, unless you do plan to spend some time on the mainland. Jaguars are nocturnal and the birds ( well they are in fence ) are sometimes seen in flight, but not as readily available as some say they are. Make the Zoo one of your trips if you wish to see the wildlife.
Have you already chosen your full trip to be on AC for lodging? If not, make a couple days on mainland. You will be doing yourslef a favor.