La Baule is about one hour drive from Nantes.
La Baule-Escoublac train station is accessible directly by high-speed train from Paris (Montparnasse station) in three hours. You can also reach it directly from the Roissy-Charles de Gaulle airport in about four hours. From Nantes, traveling with the regional train (TER) is slightly longer but cheaper, and no reservation is needed.