Last night, I attended a UKIE/Scottish Games Network session on the new tax credit system for those games things. The fact I ran away at the end is no reflection on the session itself, which was very informative, but more of the fact I wanted to go home.
Anyway, one thing that struck me was the terminology in use. Generally speaking, the industry talks about "games development" or about games being "in development". That sounds fine, but the word used last night over and over was "production", a word I've used in the past when trying to differentiate between prototyping/noodling and actually making a thing. I think more people should use the word "production" in this way, because the scheme interprets "development" as an exploratory phase, for example attempting to identify the viability of a mechanic - which explicitly isn't allowed as part of your claim.
It sounds like a tiny technical pedantic detail, but it is on such tiny technical pedantic details things can fall through. It also puts things on a par with other industries (a film "in development" is not the same and equal to a film "in production"). So if you're planning on using the scheme, be careful on how you word things in your supporting documentation. And it should make things clearer to people inside and outside the industry, which can only be good.