Will be arriving from Antony on RER Blue to Gare du Nord to then need to get the Eurostar to St Pancras. Please can you let me know how long it will take to walk from the arrival platform from Antony at Gare du Nord, to the Eurostar platform, are they both within the terminal as I can't seem to find a map? Thanks
The walk from the RER B platform (underground) to Eurostar platform (at ground level, but entrance/ticketing is done one level above ground) is done same station, Gare du Nord, just different levels and sections. The walk from RER to Eurostar should take about 10 minutes without any wrong turns and some foot traffic.
When exiting the RER train onto the platform at Gare du Nord, keep your eye out for signs reading Grandes Lignes. Follow those. That is where the Eurostar is located. When you arrive at ground level, you will likely see signs for Eurostar in addition to Grandes Lignes. The entrance for Eurostar is one level up from ground level, with a large marble staircase & escalator leading up to the check-in, opposite of the train platforms lines.