Here are some website links that you may find helpful:

https://www.gov.uk/guidance/cites-imports-and-exports

https://www.namm.org/issues-and-advocacy

http://www.americanorchestras.org/advocacy-government/travel-with-instruments.html

http://www.musiciansunion.org.uk/Home/Advice/Playing-Live/Touring/Travelling-with-an-Instrument