This really is a recipe that needs to be eaten right away - the fish won't reheat well and you'll lose the crispiness of the batter. However, there are ways you can get ahead so that the actual cooking is easier. For the chips, you can par-boil the potatoes and toss them in polenta up to 24 hours before you want to cook them (just pop them into the fridge). You can mix the dry ingredients for your batter ahead of time, then mix through the beer when you're ready to fry.