We go Florence to Milan for a night train to Arles France. Storage there for large bags?
Is station close to anywhere great for dinner or to see some sights? Have 3 hrs between train.
Yes - there is a manned storage on the ground level.
http://www.milanocentrale.it/en/service/detail/left-luggage1
Yes Victoria, but there can sometimes be lengthy lines to leave or claim your baggage, so be sure to leave enough time. And note that the storage fee is €6 per bag.
What train do you have reserved? I don't believe there is any overnight train from Milan in the direction of Arles without leaving you sleeping in a train station for the majority of the night.
There is a bag storage office at Milano Centrale. When you leave your bag, note their opening hours for pick up. When I stayed near there, I enjoyed dinner at La Buca at Via Napo Torriani 28; opens at 19:00 as do most other restaurants.
You can take the Milan Metro four stops on Line 3 (yellow) to the spectacular cathedral (Duomo) and adjacent Galleria shopping zone; beware of pickpockets on the metro and the Duomo square. Going up on the roof is cool.