How much is the use of internet on an iPhone 4 on a UK sim, in France?

go to mc Donald's and its free wifi there are lots of mc Donald's along the way or you hotel or apartment will have it the wifi will be like a daily rate so you can connect to the wifi for the whole day for 3.00€ or something like that when i was in france there was so many places with free wifi and if they didn't advertise it they still usually had it can you help answer my question anyone