If you are flying into London, you will most likely be landing at London Heathrow (LHR). From there, you should take the Paddington Express train into central London and then a taxi to Kings Cross Station to catch a train towards Edinburgh.

If you are flying into Scotland, you will most likely be landing at Edinbught (EDI).

From Edinburgh, there are several options to get to St Andrews:

• Train
  When taking the train to St Andrews, you will disembark in Leuchars, which is the nearest town with a train station. The 99 bus runs from Leuchars into St Andrews every 15 minutes, except for between midnight and 6:00 AM (Checkout the Lothian Buses Website). During most of the day there will also be taxis lined up outside of the Leuchars train station.
• Bus
  Visitors looking to travel to or from Edinburgh should look out for the X58, X59, and X60 route from Stagecoach Buses, which take around two hours.
• Taxi
  You can reliably find taxis near Waverly Train Station in the city center of Edinburgh.  Taxi fares to Edinburgh range from £50-£70. Ubers are also available but less reliable outside of the city center.

If you are arriving into Leuchars late at night, you should arrange to be picked up by a taxi.

Resources

Travel Arrangements