Hi Susan,
I hope you enjoy your first Just You trip! Trust me, it is only natural to have some nerves - but they will soon disappear when you meet up with your fellow travellers.
In terms of optional excursions, this is completely your choice. Some people will prefer to book before they depart so it's one less thing to budget for while you are away. Others will wait until they are overseas. On this tour, many of the excursions are only bookable when you are away but there are a couple that, if you would like to, can be booked beforehand.
Kindest regards,
Julia