Regardless of the season in Brittany, you should bring at least one warm outfit (pants, sweater, socks, closed-toe shoes, rain gear) and one light outfit (skirt or shorts, t-shirt, open-toe shoes). Here, it's said that all four seasons can be experienced in one day! Also, remember to bring gloves, work clothes and shoes, and a swimsuit for swimming. Nights can be chilly, so bring a good, warm sleeping bag and an insulated sleeping mat.
You can also bring recipes from your country/region, musical instruments, and games. Don't hesitate to share your culture as much as possible with the other members of the group!
The last day is dedicated to departure, usually in the morning.