Lynne comes into the room with a bunch of flowers. She sees George at the computer and asks him how he is finding Lynne's book 'My Autobiography'. George says that they say everyone has a book inside of them but that in most cases, is where it should stay. Lynne throws the flowers at him.
When Lynne comes in to ask George how he is finding her book, she is not asking his opinion on it but how he is finding the file. Lynne was worried it was lost because all she could see in the monitor was her own reflection, because it was in fact a mirror.
George's comment is referring to the fact that Lynne's book needs to stay inside her for the moment because he can't fix the computer. He is buying himself some time so he can finish watching the snooker. When it is over, he will put the small television back with the ZX Spectrum and Lynne will be able to continue her work. He actually thinks it's a good idea for a book, but his need to watch the snooker is greater than encouraging his wife in her hobbies.