Teo

Not if you're U18, and have no UKARA. Even then (if they write your number on the side of the box) customs might seize it randomly.

Same with TaiwanGun / Gunfire etc (outside UK) but lots of people still use them.

with no UKARA I wouldn't chance it. My last order from Japan had my UKARA number with the UKARA logo next to it in BIG letters on the outside of the box and I still had a 7 week argument with customs via post. Without UKARA I can only see one way that argument would have gone.