Treat the airport as the first transport decision of a UK trip. Heathrow and Gatwick suit most long-haul and European arrivals. Stansted and Luton suit many low-cost European tickets. London City suits a short runway and a Docklands hotel. Full neighbourhood logic lives on where to stay in London.
Heathrow (LHR)
The default long-haul gateway. Elizabeth line and Heathrow Express both reach central London; Piccadilly Line is slower and cheaper. A pre-booked transfer earns its place on a late landing or heavy luggage — see airport transfers. Hotels near Paddington pair well with Bath trains; King's Cross travellers should budget Tube time.
Gatwick (LGW)
Gatwick Express and Thameslink into Victoria / London Bridge. Strong for Brighton weekends and South London bases. Less convenient if your first long-distance train leaves from Euston or King's Cross the next morning.
Stansted (STN) and Luton (LTN)
Coach and rail links into the north and east of the city. Fine for a Shoreditch or King's Cross pin if the schedule works; painful if you land late and still need to cross to Paddington with suitcases.
London City (LCY)
Handy for Canary Wharf and short European hops. Not the airport for a first-time tourist with a Tower Bridge hotel fantasy and three bags.
Local transport once you are in
Contactless bank cards usually beat buying a visitor Oyster for short stays. Cap daily and weekly automatically if you keep one card. For leaving London, national rail is the UK default — start from the UK Rail Travel section.