The lighthouse is on land but it cannot be reached without scrambling over rocks that are almost certainly under water at high tide. I suppose this makes it a tiny tidal island. The OS Streetview background layer actually gets this rights. So one simple thing we can do is add it as a place=islet to align the OSM data with the OS data?

The other thing is that the path is under water in some places according to the OS data. This is definitely not right. But I'm not sure if there's a systematic solution for this.. I don't really want to go dragging individual nodes around when the rest of the coastline follows the OS data...