Thought I'd pitch in on this conversation with my 2 cents (or pence) worth! I'm a chef and can shed a little light on tips and tricks. If you're using a specific recipe, it may be a bit tricky to convert it to another system (eg UK to US) because except for teaspoons and tablespoons, pretty much everything else is different in measurement. You have a US fluid ounce which doesn't equate to UK ounces exactly. Thus 8 US fl oz is 1 cup, which is slightly less than a UK cup (48mls or so less). Remember that depending on whether you sift your flour, 500 grams could be a different volume from one day to the next. Weight will always give you the same amount no matter what. US measurements of 1 1/2 cup of flour are rough generalisations and can still be off if you scoop the flour with the cup or spoon it in and level it off.
Baking is a bit of chemistry and you have to get the chemicals (salt, baking soda and/or baking powder) in the right proportions or you won't get a reaction, that is raising effect.
So, to sum it all up, if you're going to be making a lot of recipes from both countries, invest in two sets of measuring cups from each and a good set of digital kitchen scales.