The dress code for a pirate themed hen party is quite simple all you will need are 3/4 length trousers, ruffled white shirt, pirate hat a bandana and an eye patch. Dont forget to wear eye liner to complete the look. Check out Pirates of the Carribbean for some more inspiration.
Some of the hens might like to come as tinkerbell or Peter Pan either to change it up.
When it comes to pirate food themed parties I dont think you will get away with a pirate diet have fun with it and go for platters of veg, fruit, Devilled eggs.
Bunting, Barrells if you can get your hands on them, treasure Chests and some candles of course