Sorry to take 4 mos to respond to your question! I am usually on the Band forum.
I have never taken a group to Europe, but I have taken groups overseas. Last April, I took our concert and jazz bands to Hawaii and the overseas rules applied. We rented the drum set, amps, bass, keyboard and guitar. It was expensive, but it solved two problems: having to schlep the equipment around to hotel rooms, etc and the problem of air travel. I asked local professional musicians and local band directors and found that they did the same thing. You show up to the gig and the instruments are there, ready to go. One thing to beware of, though – the quality of some of the instruments was not the best. If you rent, be sure to interrogate the rental people thoroughly about the quality that you expect. Hope that still helps.