It all seems a bit improbable to me.
For instance, How would overseas clients comply?
and... Why only deer?
If such competence is required it should surely be required for ALL species of quarry, including vermin.
Of course, with politicians in charge anything might happen. I mean, a generation ago, who would have ever have thought we could get saddled with the nonsense that is the land reform scotland act?
On the other hand, if some education and certification was to be made mandatory prior to issuing a simple, straightforward, open, FAC for up to say 5 guns, of any suitable calibre for any quarry available combined with a sensibly generous ammo allowance, like some of our Continental neighbours do it. Then, maybe that would be a really good thing from lots of different perspectives.