Originally Posted by
bseller
After you clear customs and security on the way out, just ask or look for a sign directiing you to the office. Very near the security entrance at T3, IIRC.
I did it at T3, but IIRC, it is in all Terminals. You may want to check out whether it is airside or landside before you go, however.
Rooms and opening times are detailed here:
http://www.bia.homeoffice.gov.uk/man...roomsandtimes/