Being a parent is the best thing ever and the toughest thing ever. Having my son grow up and becoming independent made me so proud, and yet so Momma bear mode it was crazy. You'll always be a Dad and she will appreciate it, maybe not now but for sure later. :-). I hate to admit it but even while my son was at Parris Island, I kept track of his daily schedule so I would know what he was going through.
I hope your daughter enjoys her trip and that she appreciates her time in Europe. She'll be home before your know it with stories and memories that will last a life time.