The entire journey of 22 miles is certainly a challenge for everyone, especially children.  However, many children have walked the entire route. Some families bring strollers or burleys to assist their children should they get tired.  Like adults, children should train to ensure they are physically prepared for the journey.  As an alternative, you can participate in the Walk with the Children which is designed for familes with small children.  That route is only 1.7 miles long.