The lights are down and the audience are in place. However George is intent on ruining it for everyone by talking. He had the entire previews and adverts to ask Lynne about the film. We can only assume that George had to meet Lynne there instead of arriving together. This may have been to do with a long day at the office, but George is not wearing a suit. The likely excuse is that he had to park the car, thus letting Lynne get out and buy the tickets. Still, the film has started and no one else is talking.
Lynne must like to thoroughly research the films she watches before going to see them as she knows what the critics think. This begs the question why she is seeing this film if it is perfect for insomniacs. By George's reaction this means that the film will be boring. There are further explanations for Lynne's decision though. The first is of course that she has a very poor grasp of the english language. She doesn't quite understand the meaning of insomnia and she may believe it has something to do with Wimbledon.
The other explanation is that the perfect for insomniacs because it tackles the issues of insomnia that non-sufferers do not understand. Lynne herself suffers mildly from insomnia and would love to see how someone else tackles the issue in a sympathetic and artistic way. George's surprise is due to the fact that he has been oblivious to Lynne's insomnia all these years and now feels bad that he hadn't picked up on it. This film is now also perfect for George to understand the suffering that Lynne goes through most nights.