You don't say where "it” is. But “it” doesn't seem to have loaded the new timetable (from 11 December) yet.

However, the best website to check Eurostar availability is:

https://www.b-europe.com/EN/Booking/Pass#TravelWish

You can book 180 days in advance, also from 11 December. If you book your return journey in the same booking, then you pay the booking fee only once.

There are some major engineering works that day in Belgium as well (November 11th, also on November 12th). There will be no high speed trains between France to Belgium that day (Thalys, Eurostar, TGV). It might be a possibility that there are some repercussions for the Eurostars London-Paris (extra stops in Lille). Or they haven’t worked the alternative timetable yet.

https://www.b-europe.com/EN/Disruptions

I think you should try to contact Eurostar directly, via fb-messenger or the contact form to know what’s going on.

Also, please note that the 11th of November is a major public holiday in Belgium and France (Armistice), so perhaps all the trains are fully booked for the long weekend. 

Did you try to book a Eurostar London-Lille? There might be some vacant spaces on those trains. In Lille there are easy connections to Paris via TGV.

Also be aware of heavily booked trains that day on almost every TGV/long distance service in France that weekend.

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