This site describes the health and safety regime covering work with genetically modified organisms (GMOs) in contained facilities, such as research laboratories or biotechnology production facilities.
Guidance from the Scientific Advisory Committee on Genetic Modification. If you follow this guidance you will normally be doing enough to comply with the law.
The primary piece of legislation that applies to the use of genetically modified organisms in the workplace is the;
Contained use of genetically modified organisms - 
Contained use of genetically modified organisms - Excluding information from the Public Register