London to Paris

" Any suggestions? " You have a plan here that requires at least 14 days on the ground- you have only 9 ( you are counting your arrival day in London after your flight- one half day, at best ). Assuming that your return flight is set from Venice, you should consider going directly from Paris to Venice. Please delete your duplicate thread. Have a great trip!

Are you referring to Perpignan France? If so, why do you want to go there? I agree that you should fly from Paris to Venice. It will be pushing it to see London, Paris and Venice in the time you have.

Any suggestions ? Sure, schedule at least two weeks or a bit more. Need to explain Perpignam. You should book the EuroStar yesterday to take advantage of discount. Or at least tomorrow. You will lose a day getting between Paris and Venice and best to fly using a discount airline but watch the extra fees.

I really don't think you have enough time for all the places you have mentioned. Unless you have a very specific and mandatory reason to to go Perpignan, it needs to be deleted from your itinerary. Spend 4 nights in London, 3 nights in Paris, and 3 nights in Venice. You are done.
If you have to go to Perpignan, then fly from Paris to Southern France, and then fly to Venice having eliminated a night from Paris and Venice each. But, I have to tell you, that is a horribly rushed and rather unpleasant way of seeing the locations.

Personally unless you just have to go to Perpignan I would spend the time between London, Paris and Venice. But I guess you could do it this way: 9/7 Arrive London (pooped out) 9/8 London for real 9/9 Mas London for the day then the last train to Paris 9/10 Paris 9/11 Paris 9/12 Morning Flight to Barcelona, drive to Perpignan 9/13 Perpignan 9/14 Drive to Barcelona and fly to Venice 9/15 Venice 9/16 Venice
9/17 Fly home

Don't go to Perpignan this trip but if you do, don't fly to Barcelona. The train from Paris is 5 hours, you won't be able to beat that. Of course if you are willing to save Italy for another trip you can have a great time in Provence and Languedoc, and you might even want to finish in Barcelona and fly home from there. Otherwise from Perpignan I'd look into flying to Italy from Toulouse or Marseilles.