better be going
(one had) better be going
Said when one is about to or needs to leave. Well, we had better be going. It was lovely to see you, as always. Better be going before I miss my train!
(I'd) better be going.and (I'd) better be off.
an expression announcing the need to depart. Bob: Better be going. Got to get home. Bill: Well, if you must, you must. Bye. Fred: It's midnight. I'd better be off. Henry: Okay. Bye, Fred. Henry: Better be off. It's starting to snow. John: Yes, it looks bad out.