In this free British English lesson on YouTube, Chris explains nine useful expressions (some idiomatic) to enhance your vocabulary in different situations:
You’re busy (or too busy): I’ve got a lot on my plate / I’ve got too much on my plate.
At the start of a meal: Tuck in.
You really don’t know: I haven’t (got) the foggiest.
You’re feeling unwell: I’m under the weather.
To ask if someone’s feeling / getting better: Are you on the mend?
You’re annoyed or angry: I’m cheesed off. “My mother-in-law is proper cheesing me off.”
Can I help you: Do you need a hand? Do you want a hand?
To say “you’re welcome” to someone: Don’t mention it.
To ask someone how they are: How have you been?