Hi Balise
You didn't say where in France you wanted to go to so this may be of no use to you - here goes anyway. I've travelled between Barcelona/Paris and Madrid/Paris quite often on the RENFE Tren-Hotels which offer a very comfortable service. The fare is about £120 return which includes a bed in a 4 person compartment as the train leaves at roughly 7pm each evening from either city.

I've also travelled by train between Madrid and Barcelona. I know it takes longer than the plan, but for someone who has a phobia about flying its the best option! Trains leave Madrid four times each day 7am, 9am, 11am and 10pm and take 7 hours except the sleeper which takes 9 hours. The fare is about £30 single plus a £24 supplement for the sleeper.

Have a great time in the wonderful Barcelona, you'll love it.

Honest Goose