at a loose end 
Meaning: If you're at a loose end, you have nothing to do.For example:
Note: This is similar to the American idiom "at loose ends", though the American idiom seems to indicate a state of unhappy restlessness that results from having nothing to do, while the British idiom simply means having nothing to do. - If I'm ever at a loose end, I look for a good book to read.
- Give me a call if you're at a loose end and we'll go and do something.
Variety: This idiom is typically used in British English but may be used in other varieties of English too.