Unlike nearby Ban Krut, the beach accommodation is quite isolated from both Bang Saphan Yai and Bang Saphan Noi, meaning that unless you have your own transport, you're quite restricted in your eating options; there's nothing in the way of local eateries, so you'll be spending a little more too.
Roytawan is the breakfast pitstop doing both Western and Thai food from 09:00 onwards and they also do a good coffee. We wish they opened at 08:00 though! Right next door you'll find Why Not Bar, which is open for lunch and dinner and does reasonable Thai food at not outrageous prices and serves cold drinks from the attached bar. This is a good spot for a breezy afternoon of grazing and gazing out to see.
A little further down the beach is a beach bar attached to Coral Bay Resort and then, after that, the best restaurant in the area, I Ta Lay. They do a broad range of Thai food with both seafood and upcountry dishes covered. We had a couple of meals here and enjoyed both the food and the friendly manner of the staff -- a welcoming option that's popular with Thais.
If you're hankering for some European fare, Coral Bay is the place to try, with a quite comprehensive range of European meals -- no doubt to satisfy their predominantly European clientele.
Heading a little north along the beach is the small beach bar at CoCo; this and Why Not Bar are the two resident expat drinking holes. CoCo also has a restaurant but it was closed for low season when we passed through.
Further afield, if you have your own transport, are a clutch of seafood restaurants to the south near the Su Chart Boat Tour pier (about 20 minutes' away by motorbike) while to the north, between Bang Saphan Yai town and the headland, are some seafood restaurants as well. We were recommended the restaurant and bar opposite the Ladawan Hotel and while we didn't try it, it didn't look too bad. Further along, almost to the bridge, are a bunch of A-frames by the beach edge, that looked to be more our style. Note that to reach both of these areas you will need your own transport.