Sure they matter, but only to the extent that foreign expenditures are a part of your costs. I.e. sure when you go to the US and have to buy USD with GBP you'l

Sure they matter, but only to the extent that foreign expenditures are a part of your costs. I.e. sure when you go to the US and have to buy USD with GBP you'l be at a disadvantage, or when you buy some electronics priced in USD, but how big a portion of your spending is that compared to food/rent/commuting/hobbies etc., all of which are priced in your local currency.