✔ 最佳答案
For the 5 London airport --> Luton, Stanstead, Gatwick, Heathrow and London City airport, the nearest one to 市中 心 is actually City airport, 45 mins by DLR + London underground. The rest of them will take around 1 hour by train. However, there may not be many flights from Barcelona to London City Airport.
From Barcelona to London, if you are travelling by Iberia or BA, you are likely to arrive at Heathrow or Gatwick.With Easyjet / ryanair, you are likely to use Luton and Stanstead. Therefore, it depends on the airline you are travelling with.
Note that if you are staying west side of London, Heathrow is the nearest. South side = Gatwick. North = Luton; north East/east is stanstead / London City airport.
Hope this helps.