Notes on Measurements and Ingredients
Measurements
I can't help it, I still think in pounds and ounces! When I do use metric quantities is when I bake with butter, simply because it comes in 250 gram packets. Whether you choose to use 25g or 30g as an ounce isn't really important as long as the proportions of one ingredient to another remain the same. More on this anon.
Ingredients
Flour - I use the cheap supermarket stuff and never have any problems. If I am making cake I sift it, otherwise not. You can use part wholemeal in any recipe but maybe not more than half and half otherwise things get a bit solid.
Sugar - I hardly ever use castor sugar, granulated is fine for almost everything. Pop! Did you hear that? That was a myth exploding.
Butter / Margarine - Take your pick, butter obviously tastes nicer, but unless it's fruitcake or shortbread I often use a polyunsaturated marg. One vitally important point is that whatever marg you use, it must be 70% fat. Many are only 59% and this just won't work.
Eggs - Generally I go for large, but if medium are what you have it won't make a huge difference. A cake might not keep just as long, but that is never usually a problem is it?