Cambridge is a mere 50 mi (80 km) north of London, and centrally located for the rest of East Anglia - with good rail services and road communication links, Cambridge is easily accessible, whether travelling by car, or by public transport. More details available on WikiTravel, here.
Cambridge is within easy reach of some but not all of London's international airports.
London Stansted is 30 mi away, for example, has regular bus and rail services into Cambridge. Direct rail services leave every hour from platform 2 (to Birmingham New Street) and take about 35 min with a return fare £12.80. For more frequent services take the Stansted Express to London from platform 1 and change at Bishops's Stortford or Stansted Mountfitchet, taking about 50 min. Note, however, that rail services may be unavailable if your flight arrives Stansted very late or departs very early in the day, and while the airport likes to advertise hourly services, there are some strange gaps in the timetable so check the boards before you buy a ticket, and go to the bus terminal if there is nothing sensible on offer. National Express coaches run between Cambridge and Stansted (including late at night), taking about 55 minutes and costing £11.50. Abacus Airport Cars Cambridge rides there from £40.00 one way.
Luton Airport is best reached by National Express Coach, taking about 1.5 hours and costing £14, but these run every only every 2 h or so.
London Stansted and London Luton airports offer many of the cheapest international flights to be found in Europe, with many of the big low-cost European airlines such as Easyjet, Ryanair and TUIfly having a hub at one of these two airports.
Heathrow is 90-120 min away by car, depending on traffic. National Express Coaches to and from Heathrow central bus station take around 2.5 h for £25. A less comfortable but cheaper and faster option is to take a train to King's Cross and then use the tube, taking about 2 hours total and costing £22 (less if you have an oyster card). Abacus Airport Cars Cambridge costs £85.00 one way.
Gatwick is the least convenient London airport, being on the opposite side of London: driving necessitates a tour of the M25 London ring road and takes around 3 h by car. It is best reached by train to King's Cross, walk to St. Pancras and train to Gatwick (or by connecting by tube to Victoria and then catching the marginally faster Gatwick Express) with a total journey time around 2 h for fare £28. Abacus Airport Cars Cambridge rides there from £100.00 one way. There is a National Express bus service available, again around 3 h (and that M25 again).
London City Airport is best reached by train to King's Cross, then Underground and Docklands Light Railway across London, tfor £22 (less if you have an Oyster card). Abacus Airport Cars Cambridge rides there from £77.00 one way.
Cambridge has its own airport, but there are currently scheduled flights only to France, Italy and Jersey.
Regular trains run from London (King's Cross and Liverpool Street) to Cambridge. The fastest "Cambridge Cruiser" services to and from King's Cross run nonstop and take under 50 min, generally departing at :15 and :45 minutes after the hour. "Semi-fast" services stop at a few intermediate stations and take about 65 min, slower stopping trains may take up to 90 min. Try to avoid taking a train with more than 8 stops between Cambridge and London Kings Cross to avoid the slowest trains. Trains to and from London Liverpool Street, for which cheaper tickets are sometimes available, all take about 75 min. Direct trains from Stansted airport to Cambridge take 35 min (catch trains from Stansted going in the direction of Birmingham). Because Cambridge is one of the main junctions of the East Anglia railway network, trains also run to and fromIpswich, Norwich, Peterborough and Birmingham. See National Rail for timetable and fare information.
The train station is about 1.2 mi south of the city centre; there are regular buses to town and a taxi rank outside the station. The station has a staffed travel centre, self-service ticket machines (note that many take only European smartchip cards and do not accept cash) and automatic ticket barriers (you need your ticket to get both in and out of the station). Pay attention buying tickets as there is often a queue at the machines and none at the ticket windows. There are also ATMs, several cafes and a bookstore, on the platform accessible only to ticket holders, and a mini-supermarket in the station foyer. Note that the station is very long, with several trains parked end-to-end on the main platform, so you may need to walk a long way between trains if you have a tight connection. Bags can be left at Station Cycles just outside the train station, for a small fee.