Hi there !
You will soon arrive in France. I hope you like it.
One good operator for you could be Vectone mobile. They say they are cheaper than everyone else, and with roaming, it is the case. (I made a comparaison with other big brands, and there is no doubt.)
You can travel to most of the countries in Europe, and it will still be cheaper than all the others.
Be careful though. The network they use is not the greatest. Outsite a good covered area, your calls can be shut, and you would have to try once or twice.
But you get what you pay for. This is what I am looking for.
Have a look at their website : it is also in English :
http://www.vectonemobile.fr/
Enjoy France !
bertrand