In the news today:
"Students can't afford to eat, never mind go clubbing."
(go clubbing = go to nightclubs)
'Never mind' is used to emphasize that, although a particular thing is true, the thing you have just mentioned is more important.
It is used in negative contexts, and goes before an option, idea, situation, etc., followed by another that is less likely.
'Let alone' is also used to indicate that something is far less likely or suitable than something else already mentioned.