I hope you don't mind my bringing a sobering view to this thread: the Euro/Pound exchange rate.
Last summer the interbank rate was approximately 1.28€ to the pound; tourist rates are obviously lower. The smart money believes the Euro zones serious troubles are sorted, but the Uk is still deep in the mire, and things look likely to get worse. So, the current exchange rate is 1.15€/£1 and falling.
So if you intend to holiday in the Euro zone this year, it may pay to book sooner rather than later. However, don't blame me if the trend reverses - it's all speculation.
Regarding SW France, yes, you can get there in a day, just be aware it's a long, and relatively expensive haul: about 9-10 hours from Calais to Bezier, excluding stops; and allow at least 180€ (each way) for fuel and tolls.
Wherever you chose, have a good holiday.