I was meant to go to the store this afternoon but I got delayed." Do all Britspeakers use it this way?

This would be a slightly unusual construction in my lex. I might easily say "I meant to go...", but the addition of the "was" implies my acting under someone else's direction (which mavericks tend not to do anywayz!) But I suppose I would not blink in surprise if I heard a sentence spoken by another Brit such as this: "I was meant to go to the Doctor's this afternoon, but I had to cancel the appointment."

I could certainly easily imagine saying the other kinds of examples you suggest, implying a pseudo-fatalistic outlook: "I was {destined/meant} to be a teacher, but fell in love with a beautiful contessa instead" :)

ciao, Caterina