Aix de Provence to Marseille Airport: fly to Paris

Which date is it?
Regarding trains in May, there are many holidays in May so you can have 1 of 2 situations:
- engineering works during the holiday weekends, which delay the date when bookings open
- trains being already full on some dates: it happens a lot over May holidays, but usually not this far ahead so it seems less likely.

So you could wait a bit.
But since it's unclear how long you should wait, you could indeed get a flight, and there's no problem doing so. There are buses every half hour from the main bus station in Aix to the airport, or an Uber should cost around 40€, sometimes less. Taxis are significantly more expensive, never done it from Aix but I'd count on 60 (which is the rough fare from central Marseille to the airport).

We took that tour in 2024 and loved it. Keep in mind that almost everyone on your tour will have the same need as you - getting to the airport. We saw tour mates pairing up to share an Uber or shuttle, and no doubt you'll be able to do that too. The price was reasonable, especially when shared.

Re: flying from Marseille to CDG, our afternoon flight was over 2 hours late, resulting in missing our US-bound flight, and we had an unplanned hotel stay. If possible, aim for an early flight to CDG to give you flexibility.

Aix-en-Provence is just a bus ride to Marseille airport for about $6.00. They are frequent. It takes about an hour. By car it is about a half-hour, but a taxi will cost a lot more. (Maybe a shared taxi for 3-4 people? I don't know the fare structure.) Check the website of Marignan airport for info on getting to and from there. No TGV is needed (if even an option). Aix is only 27 kilometers from Marignan (Marseille's) airport. We have flown in and out of Marignan. It is just fine, and not giant like CDG. Our connections, however, were through Frankfurt (a better price at the time), so I can't comment on the CDG connection.

P.S. If you are entering Aix de Provence, know that it should be Aix-en-Provence. That could be part of the problem in your search. Be careful when entering names of places in France. e.g., Just entering "Aix" could refer to Aix-les-Bains. Lots of identically named places (like Springfield in the US) or very similarly spelled names. You want to end up in the correct location.
I checked the possible cost for a taxi...maybe $80-$00 dollars as the taxi might go back empty. I hope I am wrong about the price. But I would still just take the bus...reliable, cheap and frequent. Give yourself lots of lead time...don't cut it close.

Trains do not sell out months in advance. The normal train service from Aix to Marseilles Airport is a regonal train with no reservations, and no need for advance booking. And probably it is not even possible to buy tickets in advance.

What is your travel date? You could travel directly from Aix to CDG. I picked a random date in May, and saw no booked out trains.

correction $80.oo to $100.00

If it were sold out, SNCF would add additional trains.

We also enjoyed the E France tour.
And, we took the TGV from Aix-en-Provence. (TGV Gare, not in city center)
From city center bus station take the A2 bus to Aix TGV. Catch TGV to CDG.
Picking a random May date , 28th, I see 8 direct trips available for Aix TGV to CDG.
Get the SNCF app on your phone. Easy to check timetables, price, choose seats, ticket.

See time table attached for bus A2. Buy ticket from the driver. A2 continues on to Marseille.
https://www.marseille-airport.com/fileadmin/user_upload/Bus/FH_2025_A2_UK_-_WEB.pdf