EASA rules: no more alcohol 8 hours before duty, not 12, although that might be an internal company policy. ( as long as you have less than 0.02, you are ok in reality).
They can ask me to undergo a breath test anytime before I enter my aircraft, but out of public view. ALWAYS insist on that.
Once I enter my aircraft, I have command and any unpolite clowns will be thrown off.