Watford Junction is the closest station to the studio. From there you can get on a shuttle bus to the studio, which costs £3 per person for a return journey. The journey takes around 15 minutes.
At the moment all visitors over 11 need to wear a face covering on the shuttle bus unless you’re exempt from wearing one. The bus is also running with less passengers per trip to allow for social distancing.
For more details and bus times check the Studio Tour’s travel page.