As I sat and watched "A Grand Night In: The Story of Aardman", I enjoyed the story but I also had a strong feeling that the film was much more a promotional film than a complete history of the studio. Of course, it does talk about much of the history of Aardman...but it also spends MUCH more time having various folks (mostly voice actors from their films) talk about how marvelous they thought the Aardman products were. In other words, learning HOW they make their shows and films and all the history of the studio was really not the purpose of the film....it was all public relations. To me, that makes for a rather dull sort of picture--worth seeing but not all that informative.
So here's my advice...watch this film if you want but I'd rather see the actual Aardman stop-motion movies and television episodes themselves. That way I don't need folks telling me how great it all is...I can see it for myself.