If you're cold, have a nice cup of tea. If you're hot, have a nice cup of tea. They swear that the hot tea cools you off, "cleans your pores". I have trouble following this logic when it warms you up as well, but don't argue just say thank you and drink it. There is yet to be a situation that couldn't be fixed with a nice cup of tea.
A few weeks back I had to have a minor procedure that required a little local anesthetic. Once it was all finished, I gathered up my belongings and made my way to the door. Promptly I was stopped by my nurse. She looked very worried. "Oh no dear, you can't leave yet, you've not had _____". I thought she was going to say " a doctor check you out" or "your sign-out papers" or "enough time since the procedure to make sure you're all right". No, what she said was "...you've not had tea and biscuits". I was not allowed to leave the hospital because I had not been witnessed consuming tea and biscuits. Swiftly I was lead into a waiting room with other patients who were already drinking their tea and eating their biscuits. I was given tea and a choice of biscuits. Once consumed I was allowed to leave.
I'm sure that I'll touch on the subject of tea many times, but here is one tip: If you're ever in a awkward situation with a Brit, the best thing you can say is "I'll go and put the kettle on".