Important thing is that you do take note that you always have to pack something to eat and drink. Conditions could turn no matter where you launch and you could need some refreshments. Water is critical, make sure you always pack water.
To eat, really is up to you. This is a very social sport so sharing is encouraged especially when you pack something nice.
Good options are an energy bar or two, a sarmie with water and a coke for some extra sugar. Below some of the WCKAC members packing for a long day at sea. These are some serious paddlers doing serious time on the water.