Willy44,
Beware of the complexities of rules and procedures when engaging on such a long flight that entails overflying multiple countries with different flight regulations and restrictions. It suffice to say that if you do a good home work and map out the required information and pay attention to the constraints, the difficulties associated with such trips could be contained accordingly.
It would be prudent to get the respective trip kits for the individual countries that you would be overflying. Assuming you would be flying through the airspace of UK, FR, DE, AT, and HU to reach your destination, FR seems to be the most complicated airspace to fly over.
Here are some basic aspects you need to pay attention to.
1. It is mandatory to enter and depart a foreign country from an airport of entry (custom aerodromes - aerodromes with customs clearance).
- Check the aerodrome directory for the respective countries and identify the airport and airfields available to civil air traffic.
- Identify the provisions for aeronautical information services in the individual countries.
- Carefully map out the requirements for operations for aircraft and pilot.
2. Have current navigation charts handy. It would be prudent to also have paper charts though.
3. Always maintain radio communication with appropriate ATC facility.
4. Have all required identification credentials in place (license, medical, personal identification, etc)
In short, be informed before you go on your trip.
WP