We have just returned from a long weekend in Monte Carlo, but couldn’t find any E* from Paris. We could though find a couple of options from Lille.
A local train from Monte Carlo to Nice Ville in good time for the morning TGV to Paris Gare de Lyon.
Then a RER transfer to Gare de Nord took about 30 mins for late afternoon TGV train to Lille (Connection time was 1 hr) Only stressful time was getting a ticket for the RER - easy once I got to the front of the queue for the machine.
A mid centre 4* hotel and an excellent evening meal at on of the many Brasseries within 10 minutes walk ( a little expensive I admit).
Then we had the morning in Lille centre, including an excellent Breakfast in another of the great Brasseries at half the price of the hotel.
We then walked up to Lille Europe (via EuraLille shopping centre) - about 15 mins walking plus time in EuraLille for a coffee and a dash around Carrefour.
Check in for 1335 E* started at 1230 and was a bit slow for passport checks but otherwise easy, Lille Europe station is a bit stark but we weren’t there for long.
It takes about 85 mins to St Pancras and arrived on time. Easy transfer to Kings Cross (next door to St Pancras) and home by 7pm UK time.
Over 1500km in 2 days.
OOI this was the second time we used our UK travel day, both for inbound E* and UK express to Yorkshire.