I've tried boiling water on the go & taking a flask of hot water, if it's nice & calm & you've plenty of time, boiling on the go is great. If it's blowing & wet, take the flask, trust me
A couple of good cool boxes are worth their weight in gold, they are robust & waterproof & stop your provisions from getting trashed. I have a pair of Camping Gaz Isotherm extremes, they are bullet proof, watertight, can take 250kg (make handy seats). The lids lock on so you can chuck them over the side & float them ashore. I paid about £30 quid each for mine a couple of years ago at the end of the season.