London, England.... Here's an example of what British televiewers will see when they turn on their TV sets in September 22, the day Britain takes her first step into commercial TV. This young lady is known as Sabrina, a BBC discovery, who might be described as a 40-inch edition of Jane Russell. Up to this time Sabrina has never spoken a word in front of the camera. The BBC will remain a government-chartered corporation without commercials but after Sept 22 it will have to compete for viewers with the new commercial telecasting firms operating under a new government agency, the Independent Television Authority.