The possibility of the new service had come up in a local council meeting in Kent, and now more detail is available about the link.
The train will also stop at Lyon and Avignon, taking four and a half hours to Lyon, six hours to Avignon and about six hours and 15 minutes to Marseille.
On the return leg to London, the journey time will be an hour longer as immigration and customs formalities will take place in the northern city of Lille.
Eurostar currently provides a summer service to Avignon, but this link to London could prove a popular route to the south of France.
Tickets are set to go on sale in December.