The absolute minimum is 30 minutes before departure - we would advise between 45minutes to 1hr. This gives you time to get through bag scanning, passport control and up onto the platform (and a bit of time to pick up a magazine from the shop if needed)

Subject to the usual disclaimers that times are subject to change and will be confirmed in your final documents, you should arrive back at St Pancras International at about 5pm.

Kindest regards,

Julia

on the Lille trip, could you tell me roughly how long you need to be at St Pancreas before the advertised departure time, and what the rough time of arrival is back at St Pancreas on the Monday? (subject to all the usual disclaimers)