I experienced this. I only lived in the U.K. for 6 months, but the number of chiefly British phrases/words/idioms that nestled their way into my way of speaking and stayed (20+ years on) was interesting and somewhat surprising.

For example, I never said "supposed to" again — "meant to" has always sounded and felt so much better. Similarly, "can't be bothered/asked" often exactly describes the situation in a way that "I don't want to" seemingly can't.

I'd also like to add "bum bag" v. "fanny pack" was a valuable lesson and a memorable laugh.

> can't be bothered/asked

Aussie translation: https://en.wiktionary.org/wiki/can%27t_be_fucked

> can't be asked

What you heard wasn't what they were saying.