Here’s a Google Maps link to get to the main entrance of Huxley Building, located along Queen’s Gate.
Entering through the revolving doors would bring you to Level 2, where the reception is (on your right). There will be a door on your left, behind which are the stairs. Climb down to Level 1 and enter the door. There will be another door that you’ll need to go through, after which you are at a corridor.
You should see a sign that directs you to LT130. Assuming you came from the stairs, it is located at the left end of the corridor.
