On the other side of the water from Qatar and like most other airlines, we get lounge access for duty travel but not for personal travel. One exception in some cases is when some employees can use the lounge for their annual confirmed ticket.
The rules may have changed now but I have had lounge access in the distant past when using a standby ticket on BA, with me presenting my frequent flyer card. Not sure what the rules are now but I suspect not all airlines would be quite so generous now.