We always pre-book but one year we thought we would be adventurous and more "free spirited"... We had terrible problems finding places to stay and in fact found we had to drive through the places we wanted to stay at because of lack of accommodation. With a one-year-old child I would think it advisable to book. Don't underestimate the size of France and the distances you are going to travel. We are going to Provence this summer with an 8-month-old and we will pre-book our accommodation en route.
Hope these comments are useful... have a great wedding and honeymoon.
Jan Tavill