Freedom2Choose is not aligned with any political party.
It is election time so all the parties will be sending their representatives out and about to talk to the electorate. They want to be elected so this is the one and almost the only time they will actually listen to what people say.
MPs always try to justify their actions based on what electors have said on the doorstep. They often say that issues cannot be of any importance if nobody raised them on the doorstep.
Don't give them that excuse.
Ask each and every one the following question:
"What will you do to stop the persecution of smokers?"
In an ideal world you'll want to research the subject in great detail and have all your responses ready. BUT THERE IS NO NEED. They won't want to engage in detailed discussion, will almost certainly be clueless and you're not likely to persuade them of anything there and then anyway.
All you need to do is raise the subject and state your feelings.
Why not discuss this with other members of your household and find out what questions they want to put to the parties? Sometimes it can be much easier to ask someone else's questions than your own. Try pinning the list of questions to the inside of the front door. That way, whoever answers the door will have plenty to talk about.
Bear in mind that if there was a Smoker's party that every smoker voted for then we would probably win a majority in Parliament and form the next government. We are a force to be reckoned with. All we need to do is to speak up!