Some spectacular places here. Pretty certain they have a lighthouse you can stay in (don’t quote me, i could have seen it somewhere else!)
You can stay in the cottage attached to Start Point Lighthouse, just along from that photo I posted up of Hallsands, it’s owned by Landmark Trust, who own a great many interesting properties. It’s possible to rent cottages on Flatholm in the Bristol Channel, and also Lundy Island as well, I believe.
http://lighthousesforsale.co.uk/flat-holm-island/
https://www.landmarktrust.org.uk/Search-and-book/location/lundy/