Jax has some pretty isolated beaches once you are at least 5 miles south of Mayport Naval Station. And Ponte Vedra is beautiful unrestricted air space.
Beach is a great place for new pilots because few people, no roads, no trees, no buildings and lots of great scenery. Just need to choose a day with little wind and be brave enough to fly over water occasionally.
If you download the AirMap and UAV Forecast apps you'll be off to a good start.