Just because the UK and the US both speak English, the two dialects are very different, in terms of both local vocabulary and speech patterns. I can’t really describe the differences in speech patterns through text, but the intonation and syllable rhythms are discernibly different when speaking to an English person. While I do not think that I will be changing any of my speaking patterns, I have definitely begun picking up and using the British variations of the phrases I use in my nonformal conversations with friends. In addition to the obvious flat (instead of apartment/room), lift (elevator), toilet (restroom, but I usually say restroom anyways to add propriety to it) and queue (line), the people that I have met have given me new words to integrate. In Wales, for example, a cute/pretty person is “lush”, a cool person is “mondo”, and a cuddly animal is “cutsch”. In England, something really good/awesome is “top man”, “cheers” doubles as thank you/goodbye, to be drunk is to be “pissed” or “trolleyed”.
Also, through speaking to British people, no one calls the isles the UK. When referring to their country, they mostly use Great Britain or their specific region within it. Realistically, I am not sure how much everyday contact they have with Northern Ireland, but I have yet to meet someone who says they live in the UK!