If you're from overseas and your partner is British...

[yubgummy]

What have been the main challenges / culture shocks / faux pas you've committed? Either with your actual partner or with the in-laws generally? Any tips?

I'm from a Commonwealth country so there are some similarities but a few things still take me by surprise sometimes.

Being direct and honest and not realising for a long time that DP wasn't, out of British politeness!

With the in laws, not understanding the importance of offering cups of tea.

The bars closing at 23.00 and clubs closing at 02.00 ( before the licensing laws changed )
Expected to say thank you when refusing something, for example someone asking if you would like a cup of tea, which you refuse. So here you say no thank you.
People having their washing machines and driers in the kitchen.
No plug sockets, apart from shaver sockets in the bathroom.
Greasy English breakfasts and the amount of biscuits and cake choices in shops.
No bakeries open at 05.00 with freshly baked bread and rolls.