P4 VPS cannot be turned off. That doesn't seem to affect them, although the inability to stay on level hover is disconcerting. If you are planning on flying low (less than 30 feet or so), practice on land first. In fact, practice on land for everything. I fly over water lots and have forgotten to turn VPS off on a P3 (thank you DJI for resetting everything to defaults). No problems.
The only other bit of advice is to watch the wind. Beaches often have a stiff wind that switches directions during the day. What you'd like is an onshore wind - blowing to you so that the return trip doesn't use more battery than expected. If you started out that way and you get the flip, you might have issues. That said - don't push it. Especially on the first flight. Get comfortable.