the underground stop it's PUTNEY BRIDGE. To reach there you must take the District Line heading towards Wimbledon. 

From the station it is within 10 minutes walking. The studio is located inside the renowned barber "Don Bigote". You will see a big red led sign on the right window saying "Tattoo". Head in, and Shaolink Tattoo will be up at the end of the staircase. The barbers anyway they'll be more than happy to show you the way.