With the official registrations coming on September the 1st of 2018, this pre-registration doesn't give you direct access to the trip. But the first persons who'll have filled it will have a priority among the other interested persons, for joining the trip.
You have to become a member of the association, from September the 1st, and to pay the required fees if you want to benefit from this event. The definitive program shall be announced at this same date.
Any boy under 18 years old will have to come with his legal guardian, or with someone in charge of this teenager, during the trip. A parental permission will then be required, except if the parents are also coming to the trip.