The problem is, we had one smoker last year and even with his window open the smoke would come under his door into a corridor so the person (with Asama i'll add) next to him and opposite him could smell it, as could anyone going down the corridor. So, even thought it's in your room, it goes into the corridor which is smoking in a public place (in some sense of the interpretation).
Eitherway, it's a rule. I think some accommodation was fully none smoking anyway last year. From what I gathered from the cleaners last year, the people in that accommodation who ignored the rule got fined for it.
And fines at warwick work rather simply. It gets added to your student account, you get a letter and I think 4-5 weeks to pay it, by which point a charge will be added if you don't pay it. If you don't pay at all, they don't let you graduate!
It's simple. Want to smoke? Walk outside. Most accomm have some sort of mini sheltered bit by the door way. Better still, and I'm sure you've heard it all before, quit and reduce your student debt!
The guy who was the smoker quit after 2 terms, but the uni had to bill him to replace the nets which had gone yellow and the curtains which stunk. They also couldn't re-rent the room for a long time afterwards, due to the room smelling of smoke and no one wanting to go there (I had a half-size room and wanted a bigger one, but not one smelling of smoke).
BUT, it may not apply to your room, but it may do.