Honestly, you're way ahead of where I was when considering universities as this didn't even cross my mind when applying. Luckily I ended up somewhere where there's a great work-life balance or at least the type of work-life balance that works best for me, so hopefully I might be able to help a little in you finding that too!
Unfortunately, it is hard to figure out whether or not universities set this as a priority for students without talking to people who have gone there as all of the unis marketing will say that they do. Websites like WhatUni and StudentCrowd may be good to look at and see what people on there are saying as it's separate from the universities site itself. As with all review sites though there are some extremely over-the-top good and bad reviews so I'd take those with a pinch of salt but having a look through and seeing the general consensus can normally highlight what a University is good at doing and where they could improve.
I hope this helps a little and if you have any more questions please feel free to ask!
2nd year, Computer Science (Artificial Intelligence)