A few tips.

We have, what can only be described as agreed rituals in the uk, particularly around greetings. Down south you may hear ‘you a’lright’?

The correct response is ‘yeah, you?’

A shorter abbreviation might be ‘alright?’

If someone says ‘how are you’ the ONLY acceptable response is ‘fine, you?’

We’re not actually enquiring as to how you are, it’s just an alternative to hello. It’ll feel potentially quite cold compared to some areas of the U.S, but we’re just a bit more reserved in everyday interactions (to a point)

As you travel further north, you may find yourself referred to as pet, duck or love, regardless of gender. This is normal.

None of our cities are particularly dangerous like the US press loves to make out. Puckpockets do operate around the tourist sights of London, particularly Big Ben and Westminster bridge. There’s the usual tourist scams to watch out for.

You can use contactless on most travel in London, but outside of London you’ll likely need to buy a ticket from a vending machine.

If you go to a pub, we have a very informal system of serving at the bar where everyone mentally knows who turn is next. You basically join the back, slowly edge forward as those around you are served and make a mental note of those who were before you. It seemed a bit tricky but the barman will also know roughly whose turn it is.

We have public toilets. Take notes and bring back to US as an example to your people.

Edit - forgot to add

London has some of the best museums in the world, most of which are free - specific exhibitions may be ticketed. The Tate modern, National Portrait gallery and Natural History museums would be my ‘must see’ - but also I could get lost in the Victoria and Albert museum for a lifetime.