it depends. a crossbow is definitely a weapon and it's illegal
to possess or use it. you cannot import bows and arrows regardless.
you have to go to A&E and prove to them that they're purely for
sporting purposes and you're in a shooting club or similar.
nope you don't have to store your equipment in an armoury, you can
carry them around but they have to be encased in proper encasement.
make sure you have your membership card or equivalent with you at
anytime.
