If you are staying in Berjaya. This might be the nearest seafood restaurant. About 15mins drive with GPS. Waiter / waitress are friendly, food is good but there is a lot of fly and mosquitoes.
It is highly recommended that you rent a car at the airport. For 70 / 80 rm you can get a car with full tank. Get a GPS, you will need it. Driving in Langkawi is safe and traffic there is not bad as compare to other part of Malaysia.