1. The pass is issued free of charge on written application to your Firearms Licensing Office.
2. You will need to specify what weapons you are taking with you.
3. A European Firearms Pass cannot have an expiry date later than that of your firearms or shotgun certificate.
4. All weapons must be declared to customs and to the travel company carrying you, whether by land, sea or air.
If you wish to take your weapons to any other country, whether in or outside the EEC, you should seek advice from the embassy or consulate of that country. Even in countries within the EEC, other documents may be required as well as your European Firearms Pass.
heres some further information made available by the BASC
http://basc.dotadmin.com/media/transhipment_of_firearms.pdf
heres 
company policy as regards travelling with firearms....just as an example ...phone the airline before considering booking with them ....and try to get something in writing.
Special Items and Baggage Charges
Sporting equipment
Each passenger is allowed a maximum combined hold baggage weight of 50kg including any sports equipment, subject to available space. The maximum weight for any single piece of baggage is 32kg.
Bicycles (1), golf equipment, and skis, surfboards, wind surfers, hang gliders, and firearms (2)
An additional non-refundable fee is charged per item per flight for the carriage of the above items as set out in our carrier’s regulations.
Payment of the additional fee increases your checked-in hold baggage allowance (including additional item) to a maximum weight of 32kg.
Where your total checked-in hold baggage weighs more than 32kgs, normal excess baggage charges as set out in our carrier’s regulations shall apply in addition to the above fee.
Please note that sporting equipment fees will not be refunded if you change your mind and decide not to carry sporting equipment on your flight.
(2) The carriage of firearms is strictly limited. Passengers must produce valid documentation of proof of ownership and legal authority for the possession of the firearm(s). Without such documentation firearms WILL NOT be carried.' (please see "Firearms and explosives" in our carrier’s regulations [link to relevant section of carrier’s regulations].)
further notes
- Firearms and explosives. Handguns, automatic weapons, munitions, ammunitions including blank cartridges, pistol caps, fireworks, flares, smoke canisters, and crackers. Note: As an exception, sporting/competition firearms and a maximum of 5kgs of ammunition may be carried in hold luggage with appropriate paperwork, subject to available space, if declared at check-in and securely boxed or packaged. Please note ammunition must be packed as part of passenger hold baggage and separated from firearms.I
- if you are in any doubt about what items you can take or where you should pack them, call us in advance of travel or ask upon arrival at the check-in desk.