I am not a Fray Bentos pie person. Indeed not. In my view one should be able to, and can, eat on a small yacht just as well as at home. Even better sometimes because there may well be more time to prepare food, being on holiday usually. If CC Lynam managed it on his very small yawl in 1892 so can you: "The skipper cooked a magnificent stew of hare soup, curried fowl, rice and onions, which with strawberry jam to taste, was highly appreciated". As for drink, there is always room somewhere for bottles of wine, beer, gin, tonic and the crucial lemon (the addition of ice from a freezer is a bit over the top). And the whisky of course. The main problem is how to look after a basil plant - which needs light, warmth and fresh water - without it tipping out all over the galley.
The best places to stock up around these parts are in Oban, Tobermory, Fort William, Scaranish, Strontian and Bowmore. You are unlikely to find things like coconut milk in an island shop, but you never know. Many of the village shops are excellent for the basics, and more, for example in Ardfern.
Here are some recipes, provided by various friends and family, that you can prepare on just two cooker rings, and without a weighing machine (assuming you have bought meat by weight). A measuring jug is very helpful but not absolutely critical (improvise from a used milk container maybe). Having an oven is a bonus so you can bake your own bread from bread mix for example, and the grill will do your breakfast toast.