My kids are pretty well experienced air travelers and fortunately very well behaved. They are not fazed at all by the idea of traveling alone to the UK. I have no idea how the 'accompanying' happens though. Though they know about check-in, immigration, customs etc I expect that to make sure they don't make a mistake or screw things up / get worried that they'll be shown / taken through these processes at both ends of the flight and someone will make sure they are at the gate and correctly boarded. Then at the other end handed over to my parents when they arrive. I'm certainly not expecting someone to hold their hands from the time they get to the airport until they are sitting at grandma's house and sitting by them for the duration of the flight.
Correct assumption or not?