You will be asked if you’ve done ground & air schools for any commercial purpose when you try and get liability insurance. You’d get away with your ‘own’ use but flying anywhere near people I’d be wary of without proper cover. Plus the courses will show you the CAA approved way of flying with an audience which may not be compatible with a festival set up 🙂
I’ve done the ‘badges’ and I wouldn’t say they endow you with any super powers a normal sensible adult wouldn’t have, but they do let you get the insurance with fewer questions.
Alternately, if you just want to wing(less) it, bang for buck I’d look for a second hand Phantom II with a GoPro gimbal. You add on the bits for FPV fairly cheaply if you need it.