Spoilers for this quest but I'm currently doing the quest Family Matters. I've found the daughter, turned the botchling into a lubberkin, and now to get the rest of the information about Ciri I need to find the Baron's wife. The problem is all the quest says it "investigate all remaining leads in velen". That's it, not a location, not a person to talk to, nothing. What leads?? Am I meant to come back to this quest later on, is it bugged, or am I missing something?

You have to do the other main quest in Velen.

It's referring to the leads in your "where did Ciri go" investigation in Velen. You should have another mainline quest in Velen which was your other 'lead' in the search for Ciri. When you play far enough through that the rest will play out.

Ah ok, thank you!