Cannabis is none toxic, which means no one dies from cannabis. Unless criminals get involved. Take cannabis out of the hands of criminals and put it in the hands of doctors scientist and gardener baker publican chemist. So its potential can be unlocked.
Let the people grow all the cannabis they want. Tax any sales of the product by weight. All you would need is a medical herb traders licence, one of payment to the gov of £100 registering you with tax man. People could make money and the government wound make money staring with that fee everyone would want to pay. cannabis=money.