.....

I doubt a bunch of potheads marching to each government's meeting place would somehow work. In fact I think that would probably manage to do the opposite if we demanded all drugs be legalised.

I mean imagine the spectacle...
10 Downing St.

30-50 (if that) potheads shouting "We want ALL drugs legalised, don't exclude, give heroin, crack and meth out to the common people."
We would be on the front page of every tabloid being told to our faces the following morning how stupid we are.

NB: Why is it so urgent, ran out of heroin? Also I don't think urgency is going to help matters here, I don't think we're going to be able to legalise ALL drugs any time soon.

Somehow I don't think asking heroin, crack, meth to be sold in the local tabacconist will work.