• off to   (going to)

I’m off to work. See you tonight.
My parents are off to Italy this summer, so I will be home alone.

  • popping out  (going out, and will be back very soon)

I’m popping out to the shop. Want anything?

  • nipping out  (going out, back in a couple of minutes)

I’m nipping out to the bank. I’ll be back in 5.

  • heading off  (beginning a journey(short or long))

I’m heading off to work, but I will call you later, OK?
Ok, Gran, we’re heading off now. We’ll call you when we are home.

  • step out  (to leave a room for a moment)

Mr. Johnson has just stepped out for a minute, but I can ask him to call you back when he returns.
Dave, do you mind stepping out for a minute? I need to talk to Anne alone.