Don't eat cod, or at least see where it's sourced from. Cod is on the decline and there are good alternatives to cod, including Pollock, which you'll pretty much get in every supermarket now. Better to buy fresh as well.
An easy and good way to cook fish is "En Papillote" which loosely translates to in a bag. Here's a recipe here:
http://www.deliciousmagazine.co.uk/recipes/cod-en-papillote-with-tomatoes-and-pesto
Another great and easy way to cook white fish is to cut it into chunky strips, roll it in flour and then fry it in a frying pan. Use flora oil or something at a good heat and it really doesn't matter that it has been fried and serve it with some lemon and a good tartare sauce and whatever side you want.
If you want to eat fish and want a really healthy recipe, try poaching it (I'd usually use salmon but it should be fine with cod). Put the fish and your flavourings into a pan with cold water, gently bring the water up to a simmer, let it simmer for a couple of minutes and then take off the heat and allow the salmon and water to cool. For flavourings you can try black pepper, salt, bay leaves, lemon, white wine vinegar (compensate with a little sugar if you do), dill, star anise, lemongrass, chilli... all sorts really, just make something that suits your pallete.
Then to go with it, some boiled jerseys with a little butter and chives and cucumber salad, which is easy. Slice a whole cucumber, skin on, and add three/four diced shallots, 50g white sugar, 4 tbsp of white wine vinegar and season, let it sit for 1 hour at least... it's the conkers. I'd have the fish cold normally, but that's up to you.Hollandaise goes well, but negates the point of going healthy
Lastly, if you try grilling it with lime juice, garlic and chilli, that can be very nice as well.
