You need to steel yourself to the fact that your leg-covering garments should be referred to as trousers, because “pants” in the UK refers to underwear. Getting this wrong leads to all sorts of amused looks from the natives, as if you're a five year old who just said “fart” in a restaurant. You would do well to become familiar with some of the more racy differences; for instance, “fanny pack” sounds more like a verb phrase here than a noun. To be fair, we're probably the ones who re-purposed them in the first place.
A Chicagoan living in the UK finds that, although English is spoken here, the UK is still a foreign country. This is his field guide to help fellow Americans navigate the often delightful and sometimes puzzling cultural differences they'll stumble into over here.