Daytrip to Paris from London - need ideas and suggestions

TBH if you haven't purchased hated the tickets yet I'd spend at least one night in Paris. You are planning 3 hrs in Louve so at earliest will be done at 2Pm . Of you really are set on returning to Lonfon I do the hop on hop off bus tour and then just stroll around Notre Dame after snd get dinner.

When are you traveling?

I'd get a separate tour guide for the Louvre. Are you interested in seeing Notre Dame? I'd do that first and then do a timed entry to the Louvre for early to mid-afternoon to give you some flex time in case the Eurostar train is delayed. (Yes, I've been delayed by as much as an hour and a half going one way or the other.)

IF you are going when weather is nice, I'd take a taxi to Notre Dame. then walk to the Louvre. After the Louvre I'd walk thru the Tuileries to get some views of the Eiffel Tower from the edge of the garden in front of the Orangerie.

You'll have to be back to Gare du Nord at least 90 minutes before your train leaves. I, honestly, would allow 2 hours to do the border control and security checks.

We will be there in mid-May, so weather should be good, but you never know.

Because your time is so limited, I suggest not considering a car-based tour because you will waste time in traffic. Given that your friend wants to spend three of your 8 hours in Paris at the Louvre, I think a museum tour guide is great idea I suggest the tour offered by the museum at 2 PM if you are going on a weekend day: https://www.louvre.fr/en/exhibitions-and-events/guided-tours/welcome-to-the-louvre. If you are going on a weekday, A friend of mine used Paris Muse Tours and loved them (by the way, she got the recommendation from a post on this site).

Pam gave you a perfect plan, IMO. I agree about getting a museum guide, unless your friend can develop a specific plan and it doesn't include the magnet items. The rest I would enjoy by strolling, as Pam also indicated, through the Tuileries, stop into a boulangerie, patisserie, fromagerie, etc. if you have time. You'll have a great day trip!

I'd say it's still early days at ND so it's going to be overpopular, and dealing with Eurostar these days is apparently not always pleasant.

If your friend absolutely must see the Louvre, read Rick's section on how best to tackle it and reach out to his suggested guides.

Myself, I'd rather do the Orsay. And then wander around the Left Bank.

If we were to stay one night in Paris what area would you recommmend?

You should post that last question in a new thread since many people have many opinions

You should be sure to check the then current advance-check-in requirements for London-Eurostar, BOTH directions. They range from 60 to 90 minutes, for immigration and security checks. Boarding has been denied for people who arrived after the posted gate closing, but before the departure of the train. Note that cheaper Eurostar tickets have change or cancellation restrictions/costs.

Thank you! I’m aware of the requirement to be there early. That’s why we plan to be back at Gare du Nord at 7:30 for our 9:01 train back to London. :)