To find your nearest postbox, look here : http://www.dracos.co.uk/play/locating-postboxes/nearest/

To find nearest ATM machine: http://www.link.co.uk/ATMLocator/Pages/ATMLocator.aspx

Travel

South West trains live info: http://www.journeycheck.southwesttrains.co.uk/?

TFL journey planner: http://journeyplanner.tfl.gov.uk/

National Rail Live Arrivals/Departures Board: http://www.nationalrail.co.uk/times_fares/ldb/