London Stansted Airport is not really in London, but in the county of Essex, the address is :-
Stansted Airport
Round Coppice Road
Essex
CM24 1SF
Stansted Airport
Round Coppice Road
Essex
CM24 1SF
You can take the train or coach to London, but the easiest option is to have a private taxi transfer. Your driver will greet you in the arrivals hall with your name board and then escort you to your vehicle and then drive you to your hotel or address where you are staying.