If you want to bookmark a quick mozilla search from your house to another postcode you can use this URI :
http://journeyplanner.tfl.gov.uk/user/XSLT_TRIP_REQUEST2?language=en&sessionID=0&type_destination=locator&name_destination=DESTINATION_POSTCODE&type_origin=locator&name_origin=ORIGIN_POSTCODE&place_origin=London&place_destination=London
just change the DESTINATION and ORIGIN_POSTCODE to %s if you like or make it as static bookmark.