You can go to a liquor store today and purchase a lethal amount of alcohol for about $20. And it’s lawful to advertise the stuff. GHB is less harmful, but it’s illegal.
At one of the nightclubs I go to, they have fairly prominent signs warning about GHB, and telling you that you will get a lifetime ban if you're caught with it. Most other drugs will just get confiscated (and often consumed by the bouncers), or at worst kicked out for the night.
And you can’t advertise drinking. You can promote brands, but not drinking directly. Which is weird and I don’t know how the line is defined, but it exists in at least some countries I’ve been to.
As far as i know you can drink whatever you want, when you want after you are 18. Notable exception is Germany where from 16 you can drink undistilled drinks like beer and wine. Oh we had lot of fun when i was 16 on our school trip to Germany. Good times.
About advertising i think it applies again to Scandinavia.
Overall i think people have pretty positive drinking habits in europe. Most people try it early and drink quite regulary meaning they can manage it without much problems.
My experience (not scientific one) is that most of the people i know who have serious problems with alcohol nowdays are almost exclusively those who had very strict parents. Alcohol and drugs were heavily stigmatized in their families and once they are 18 (or out of parents homes) they just go nuts and can't handle it. People who gradually try alcohol tend to have much healthier approach to it.
I don't think prohibition works. Education does.
Poland, too, with the exception of beer (and this is still subject to many restrictions).