Can you “just do this” or is there some preapproval you’re meant to get beforehand? Presumably the answer varies wildly by jurisdiction.

We did it in the US, and filed a NOTAM with the FAA. The hardest part was figuring out how to convert what I had (we are launching a weather balloon from X, Y coords at Z time) to what they wanted (distance, direction, etc from nearest air tower). It's just a phone number you call, and they were pretty friendly (helping convert my lat / lng to what they needed).

There are rules you have to understand and follow, notifications required but no approvals if you meet certain criteria. It's mostly an FAA thing in the US, so one jurisdiction.