Going to be difficult:
Selling it for its psychoactive effects was made illegal with the Psychoactive Substances Act in 2016, but it is not currently a crime to be caught in possession of the drug.
while the canisters can also be legitimately bought for whipped cream dispensing.
Legal to possess, but illegal to possess for a certain use?
Couple of years back every bar here sold “balloons” filled from industrial/medical containers behind the bar. That’s now stopped, whether police action or the manufacturers I’m not sure. I do know that in the UK the manufacturers won’t sell the big jobbies without evidence that you are a dentist etc. For I looked into it, would it be possible to have a “hot dog stand” kinda retail operation in a bar area?
You know, just for research purposes.