This isn't legal advice, but we have been involved in events with venue owners who are happy to allow smoking on the premises so long as only patients are smoking.

This is legal as it is a private event in a private location and patients are consuming their own medicine or sharing. We did not provide medicine at the events.

If you are wondering if you can set up a sort of reading room where people/patients can come to smoke, I don't know where it would fall in the law.