if you enter at the entry that has the words Old Teachers College written over it, there's a small door that looks like an emergency exit that you can walk through. then there should be a flight of stairs on your left. go up two flights of stairs, then turn right (=). Then the hall will turn to the left (ll), then the right again, like =ll====. and TC 401 is down the end of that hallway.
hope that's not too confusing