Heathrow Airport is about 20 km west of central London, but it only takes 21 minutes to arrive in the heart of the city thanks to the Heathrow Express. This express train departs from Paddington station every 15 minutes with a similar service in the return direction.
Transport for London has divided the city into nine zones. Fares for each zone depend on peak and off-peak hours, but the price of a single journey is typically no more than £10. More information about the Tube and bus services can be found at the Transport for London site.
Black cabs are the way to go and can be hailed from the street or from designated stands. There is a minimum charge of £2.20 and fares are metered. Stay safe and avoid unlicensed minicabs: they are illegal and uninsured so inform yourself before hopping in.