See
http://www.vsc.co.uk/visitors_london.php
From Thiefrow Airport, take the rail link to Paddington, then the London Underground (Circle or District Line to Notting Hill Gate, then Central Line to Marble Arch); Marble Arch is very close to the VSC.
Alternatively you can take the London Underground from Heathrow (Piccadilly Line to Earls Court, then District Line to Notting Hill Gate, then Central Line to Marble Arch).
Or just get a taxi from Paddington? Don't be tempted to take one from Heathrow to the VSC as they're pretty expensive!
You can download the London Underground map from
http://www.tfl.gov.uk/tfl/pdfdocs/colourmap.pdf
Have a great visit!