There is no real road (more like a cart path) and there are no cabs on the North end of the island. The area where you are headed is 10 miles North of town and usually only accessible by boat.
I'm assuming that you're coming on a cruise ship which will anchor off Belize City. You'll have to take a day trip to AC from the cruise ship and then hire someone to take you by boat to the area you're looking at.
Don't you have a real estate agent? They should be working out these details for you.