Whether you need prior approval to fly depends on whether your location falls in controlled airspace, a no-fly zone, or a restricted zone. Without understanding this, it's common to plan a flight and only discover on-site that it's not actually allowed.
Key airspace categories
Areas near airports, military facilities, and major national infrastructure are restricted without prior approval. These zones are tightly controlled for safety and security reasons, and unauthorized flights can lead to real consequences.
What to check before flying
Before flying, check the airspace classification for your location through official public flight-information services, and apply for approval where required. Approval requests can take time to process, so for filming or commercial work, apply well ahead of your planned date.
Skipping the approval step can mean the flight is simply not possible once you're on-site for filming or commercial work, so make checking airspace part of your planning process from the very start. If you're moving between multiple locations, remember that airspace rules can differ from site to site.