Oh. Dear. Me.
This is, at the same time, one of the funniest and one of the worst films I have ever seen.
The story follows the “what would happen if fictional characters discover that they’re fictional and journey to the real world and meet their creators while attempting to halt the destruction of their world” theme.
And David Warner is in it as the evil wizard/alchemist, Dr. Pea. I have high regard for Warner and he’s excellent in everything I’ve seen him in.
He also goes a long way to saving this film. 
The bottom line is that if you like the League’s televisual offerings you’ll most probably enjoy the film. It’s not the most intellectual movie I’ve seen and there are plenty of knob jokes to keep you going.
BigAl