CDG to Eurostar

That's enough time to catch the train as long as the flight arrives on schedule. I am surprised you didn't find a flight directly to London from. Budapest at reasonable prices

Should be enough time. Just remember to allow time at Gare du Nord for security (which will be similar to an airport) to get on the Eurostar.

Seems as if it would be better to fly on EasyJet from Budapest for a little over 100 pounds. This Summer, they don't fly on Tuesdays or Wednesdays. Friday and Monday they fly out mid-day. Other days they fly around 8:00 p.m.

I would not combine two modes in one trip. Just fly Budapest to London. Adding a train ride complicates things.

You need to be at Paris Nord 90 minutes before your Eurostar Time, that is 6.40pm. A time which is non negotiable.
So that gives you essentially 3 hours to make the transfer journey.

If you have checked bags on the flight that will decrease your available time a bit. So you can cope with the flight being up to 90 minutes or so late, perhaps a bit more.

Given that this is a low cost carrier, who have minimal turn round times, and the plane will be on probably it's 4th flight of the day, I would be a bit jittery. Maybe monitor the on time performance of your flight for a week or so. In fact check that it does not have a record of cancellations. I am assuming you want to do Eurostar for the experience. I suspect I might book the last train of the night to give an extra buffer.
Spare time in Paris, if everything is on time, is never wasted time IMO.

Sounds like the time is there. I don't know who you are flying, but if it's Ryan or Wizz they have very good on-time records. While between the cost to get to Paris, the transfer to Nord and the train ticket will probably cost you twice what flying to London will cost, if you are doing it for the fun and experience then go for it and have a blast. I suspect a clandestine meeting with Natasha on the train .... (?).

But the worst that can happen is you get to spend a night in Paris. It's all an adventure.

If doing it for the fun and experience -- well don't. In our experience the Eurostar is a run down dirty train and you don't see anything interesting on the trip.

Do you already have your tickets?

If you have, you've been given good advice. Don't delay your journey to Gare du Nord. As stated, Eurostar is strict about their check in times. And anyway, you will have to go through Schengen Exit Immigration, UK passport control and security.

If you haven't purchased your tickets, would you mind sharing why you are doing this rather than just flying directly to London?

Most people are directing you through Gare du Nord, but honestly the fastest and easiest way is to go from CDG direct to Lille, and catch the Eurostar from there. See the Google Map below, showing the alternatives.

https://www.google.com/maps/dir/Paris+Charles+de+Gaulle+Arpt+(CDG),+95700+Roissy-en-France,+France/London,+United+Kingdom/@50.174552,-1.1327255,7z/am=t/data=!4m15!4m14!1m5!1m1!1s0x47e63e038e4ccf5b:0x42be0982f5ba62c!2m2!1d2.5690925!2d49.0039557!1m5!1m1!1s0x47d8a00baf21de75:0x52963a5addd52a99!2m2!1d-0.1275862!2d51.5072178!3e3!5i4?authuser=0&entry=ttu

If doing it for the fun and experience -- well don't. In our
experience the Eurostar is a run down dirty train and you don't see
anything interesting on the trip.

I am glad for the experience I had.

@SM

My experience getting the Eurostar from Paris to St Pancras. 8th April 2024 Monday just before 9am with my wife and oldest son.
Flew in from Shanghai the afternoon before and had vacillated on taking the train that evening. An 11-hour China Eastern daytime flight, so decided to overnight at a hotel nearby. Met at CDG by our son, who had flown in via Columbo a couple of days before. In morning walked to Gare Du Nord 3 hours before departure time. Through Passport and Security smoothly. Maybe just lucky. Spent the rest of the time waiting to board.

Saw the neglected parts of inner Paris that hug the railway line and enjoyed trying to translate the prolific French graffiti attached to walls, fences, and any stationary rolling stock. Like those one sees on the glossy tourist brochures. Soon gave way to outer suburbs and then the French rural countryside, which was developing a verdant green appearance. Early spring flowers were showing along the track easement. Further north power generating windmills began dotting the flat landscape.

Simple breakfast to fill a hole in my stomach. Through the tunnel. Wi-Fi allowed us to talk to our grandchildren who stayed behind in Hobart.

Through the English countryside to inner London and the once again neglected, graffiti scrawled buildings, fences etc. Quite ugly. Meaning of graffiti came naturally, could have written some myself.

Not a great train user. Last was 2018, regional train Laon to Paris for the day. Eurostar was to me comparable. Would not attempt to compare to Indian Pacific or Simplon Orient Express. A class of their own.

No opinion on whether there is enough time to connect. Depends on how courageous one is. I am not that courageous. Like to have plenty of time to enjoy my holidays in comfort. Could have flown direct to London from Shanghai. Chose to try out the Eurostar. Just for fun

Regards Ron