Ostlerjs -
Welcome to the PPrune forums. Kudos for soliciting info from those more experienced. I have read the advice to you here from others, and as it always seems to be with PPruners, it is good stuff. As far as it goes. No post here can be of sufficient scope, depth, and detail to adequately prepare you for your intended journey. This comes from someone who has monthly circumnavigated the globe. Nothing is ever the same from trip to trip.
I strongly agree with others here who suggest that you engage the services of a seasoned Lear contract pilot with NAT and EUR experience. That along with use of Jepp or Universal for handling. Don't balk at the cost. Together, the experience and resources of the Handling Company and their local agents, and the Contract pilot will make the trip run smoother and ultimately help maintain your professional appearance to your clients / bosses.
When your first overseas trip is done, you will have learned a huge amount, and you will have a better idea of what you can do yourself on the next one, and where contracted services are best employed. Good flying, enjoy the diverse and wonderful people and history on the other side of the pond, and like Westhawk, I hope the view out your window is clear.