There are 5 airports in London: Heathrow, Gatwick, City, Stansted and Luton. At the first two, there is a fast train service to the centre (Heathrow Express and Gatwick Express). More expensive, but fast and comfortable.
Heathrow is also accessible by tube, via the Piccadilly line (one hour’s journey from central London). The express train leaves from Paddington station.
Gatwick, the second busiest airport, has an express train from Victoria station. The journey takes about 30 minutes.
City Airport can be reached by DLR from Bank, Stratford or Canary Wharf. Stansted is served by express trains from Liverpool Street Station.
Passengers travelling from Luton can take the train from St Pancras International to the airport.
All airports also offer bus options from central London.

Heathrow Airport

Heathrow Airport is London’s largest airport and also one of the largest airports in the world. About two hundred thousand passengers pass through it every day. Coming from Brazil, this is probably where you will land. Located only 20 km from London, it has two main runways and five different terminals.
To give you an idea of its importance to the British nation, its terminal five, exclusive to British Airways, was personally opened by Queen Elizabeth II in 2008. It has an underground station and a railway station, making it easy for airport users to get around. Virtually every company in the world uses the airport.

https://www.heathrow.com/

Longford TW6, United Kingdom

https://goo.gl/maps/qSjFC44jDKALXLQj6

Gatwick Airport

This is the second largest airport in London. It is about forty-five kilometres from the city centre and has a very high traffic volume, especially considering that it is a single runway airport.
Although it has lost importance in recent years with the expansion of Heathrow Airport and the rise of the others, it remains a key gateway to the English capital. It has a train service, making it easy to get into the city.

https://www.gatwickairport.com/

Horley, Gatwick RH6 0NP, UK

https://goo.gl/maps/9bsHEMw2DQR3M4nV9

Stansted Airport

Stansted is the third largest airport in the region. Situated 60km from the city centre, the airport is located in Stansted, a small borough of Greater London. It has gained ground, among other things, for being the darling of Ryanair and EasyJet, which send many flights there. It also has rail services.

https://www.stanstedairport.com/

Bassingbourn Rd, Stansted CM24 1QW, UK

https://goo.gl/maps/JYC8kzbX3NHFJhfs8

Luton Airport

This is a remote airport and is actually a secondary airport used primarily by low cost airlines. It has seen growth in recent times, but the distance does not attract many tourists or major airlines.

https://www.london-luton.co.uk/

Airport Way, Luton LU2 9LY, UK

https://goo.gl/maps/nMuci9Gf91iHskH48

London City Airport

This is the airport located 10km from central London. It has a single 1500 metre runway and handles short-haul flights and also some flights from New York. The airlines that use London City are: British Airways, Alitalia, Blue Islands, CityJet, KLM, Lufthansa, Luxair, Sky Work and Swiss International Airlines.

https://www.londoncityairport.com/

Hartmann Rd, London E16 2PX, UK

https://goo.gl/maps/9GdJdbJSnH799q56A