It was fabulous - worth all the effort involved! Well, I said I'd report back, so here goes, sorry no photos were allowed :(
In someways the exhibition was quite simple and it would've benefitted from a catalogue or guide booklet. It showed the progression from original illustration to printed book and then through storyboard to cells and final screen. Most examples were traditional animation with overlays of cells, but there were also some more recent examples using digital animation.
There were 2 presentation running (sometimes it was difficult to focus on only one ...) one covered more of the digital side and the other showed several animated films being made traditionally (eg Raymond Briggs' "The Snowman" and Beatrix Potter's "The Tailor of Gloucester"), both were fascinating.
Beatrix Potter is one of my all time favourite artists and it was a thrill to see an actual original illustration by her. (Wow!!)
I'm kicking myself now though, I wish I'd gone a few weeks ago and then I could've had a second visit. I often find that with exhibitions, after I've had a chance to think about what I've seen, I want to go back and check things out again.