I could suddenly pick other Americans out across the room by their accents, and I became conscious of trying to make my vowels sound less American. I found the Northern English accent more difficult to understand, but the feeling was mutual in one instance. Food was always a challenge. Herbs are herbs, but with the h pronounced. I first learned this at a student grocery store from a sign that was clearly put up for clueless Americans.
Sandwiches are a whole other ballpark.
Tomato isn't a topping, but a filling. Schoolwork produced its own words. We might have 15 hours of class a week, while a social science or humanities student in Britain could have as little as four hours total. On the other hand, the natural science and engineering students have a similar load to Americans. Adjectives always amazed me.