The one thing I'm curious about RE film is how it'd... well, work. The reason they can get away with it for Day of the Doctor is because it's also on TV at the same time, but I remember RTD saying ages ago when asked about a film that part of the problem is the way the license fee stuff works means they're not allowed to put anything 'vital' in a venue that can only be accessed by paying money. So it'd have to be a spin-off, or something weird like that.
Does anybody know how these BBC guidelines work in detail?
I imagine it'd simply be a standalone adventure, or one that slotted into the continuity in a nondescript place. So long as it wasn't required watching to understand the TV show, they'd be good to go. That's my understanding of it anyway.