As you can imagine, me I'am not common with the document rules in Great Britain. It seems like his Last Will and Testament is or was available as a little book / Print Magazine.
I was able to find two snippets of it...
Someone in possession of the whole thing ?
He signed it on 17 th September 1991...any conflicts with the Queen Party Line / MIH Production etc ?
He signed that just two months before he died. Presumably there was a preexisting will cos it feels like he was cutting it pretty close given how precarious his health was at the time.
The only thing I can hang some hope on is that I'm sure the official Queen website posted a news item about this a long while back when it was announced, so it could be being made in collaboration with them, and so will be 'approved'.