It is also the arrival and departure spot for the Channel Tunnel which crosses to Calais in France, the Tunnel is located north of the city at exit 11a on the M20. It can also be accessed from Folkestone downtown by heading along Cheriton Road (A20) which becomes Ashford Road passed the M20 exit 12, there are also buses going in that direction nearly to the Tunnel entrance.
As of 2011 there have been reports of the eurotunnel company refusing people who are identified as hitchhikers by the drivers. Tell your driver to not mention that you're hitchhiking.
Folkestone is located just off the M20 which is also the junction to go into Sussex, following the coast on the A259, when coming from Dover.