A family trip

Hi all,
My husband, my children, and I will be traveling soon to London, England in a week. We are going for two weeks. The trip is mostly for the children to get acquainted with their cousins, aunts, and uncles on their daddy's side. We are also throwing a party for my mother in law. Everything is set, however I am beginning to get a sort of traveler's anxiety. I want to be strong for my children because this will be their first time on an airplane. My son's excited and eager to meet his family and to get to know them. ( He's seven) In addition to the family experience, I expect to take him along to see all the landmarks and to tell him about England's rich history. I want this experience to be truly memorable for him. Has anyone else ever had this kind of anxiety associated with traveling? Past or present?