The cottage is just a short walk to the beach crossover (200 yards), right next door to a large beautiful swimming pool, and 150 yards from a tennis court. The beaches, pool, and tennis court are un-crowded year round.
(It looks like it is in a development across the street from the beach.)
I don't know the house personally, but the web site says it's in Grove by the Sea. That's north of 30A. Maybe 1/2 mile west of where 395 intersects 30A. Whether the walk to the beach is too long depends on how much stuff you've got to carry, how little your kids are, etc. I live about 300 yd. from the beach and it takes me 3-5 minutes, I guess.
I happen to know the owners of this house. It's a great rental and is on the south end of Grove by the Sea, so it's as close as you can get to the beach in Grove by the Sea. It's also right next to the community pool.