We arrive at Charles de Gaulle APT from Aust via Hong Kong at 4.40 pm and want to fly to Axe en Provence that night do you know how long we will need to clear customs and transfer to another airline maybe 2-3 hours. Or should we just overnight at the Airport hotel and fly out next morning. Would really to prefer to fly out that night.
You could fly to Marseille to get to Aix-en-Provence. I would leave four hours for an unprotected connection like this one will be. You could also take the train directly to Aix from CDG if you are so inclined. There is a direct one at around 7:30 PM getting you to Aix at 23:04. There may not be any flights that you can plan on taking until after 9 PM and that would get you to Marseille at a round 11 and then you would still have to get to Aix. I think that heading to Aix on the day that you arrive from Australia is a wise move.
I agree with JHK in recommending train to Aix. I did this once a few years back, although my arrival at CDG was via Singapore and the flight arrived around mid-day. Back then, to get the train I had to transfer to the Gare de Lyon (easy even with luggage on the Air France bus), but the train was very restful after all that long-haul flying. Good to be able to move around freely and even doze a little to catch up on jet-lag.
It's a 3 1/2-hour TGV ride from CdG to Aix. As you realize, a separate plane ticket will require all the bother of finding the correct terminal, checking your luggage, security etc. In Marseille airport you will wait for your bags, then take a half-hour shuttle bus to Aix. So the time consumed, either way, is comparable. As for price, it is impossible to compare since you did not provide any travel dates. You might have been able to purchase an economical combination air ticket all the way to Marseille but it sounds as though your intercontinental ticket is already in hand. Both TGV and budget airlines price the same way. Last-minute tickets will cost double, or more, than a ticket bought three months in advance. I'd choose the comfort of the TGV to Aix.