unpaid parental leave: do people commonly use it and what for?

To clarify I'm talking about the unpaid parental leave that a parent can take up to the 18th year of their child for a total of 18 weeks. The gov UK website mentions it can be taken to spend more time with the children or to look at new schools etc. I was wondering whether it is commonly used by the UK population as I don't know of any parent in either our circle or at work that has made use of this opportunity. Is it one of those things you can do, but is frowned upon? Also I'm curious what have you guys actually used the UPL for? I'm considering using unpaid parental leave but to actually spend time away from the children rather than with, so to recharge my exhausted batteries! Bonus last minute addition: does work ask you proof you used it for parental related stuff?