well, Spain are very jumpy about drones on beaches,( too my knowledge,) unless you are in the middle of nowhere, but, you are allowed to fly out there !!.
As for packing it, It MUST go in your hand luggage, with you on board the plane.
Each battery MUST be in a fireproof holder (avail off Amazon),
with its terminals taped up to prevent a short circuit.
The batteries MUST be discharged to about 20% charge.
The batteries MUST NOT under any account be placed in the hold luggage (CAA Regulations)
I have travelled extensively over the last 4 years with all sorts of drones, and have never been challenged.
BUT, I would contact the airline and clarify there policy on carrying drones aboard their planes.
Also make sure you have PLI Insurance,
and the rules / drone code for the country in question.
If we can be of any further help, just ask !!
As a final thought, I went to Benidorm about 3 years ago, and wish now I had taken my drone, so please do not be deterred with red tape !!
I always pack my drone with my Main Camera gear in my Canon Bag, then put Controller and batteries in your other hand luggage, so as too split them up, so to speak.
Most UK Airports are now use to drones being taken on board planes ,and through security, I have never even been asked “What’s That”
Happy Travelling !!