No no no no. Please do not 'allow' your daughter to smoke.
My dd wants chocolate doughnuts for dinner every night. And she asks relentlessly every night. My life would be soooooo much easier if I said yes, but her life would be sooooo much shorter if i said yes.
This is honestly what I'd do in your situation. And i may sound overly strict. 
I'd tell her head of year/teacher about my concerns.
I'd request my dd to attend a meeting with a guidance teacher/councilor.
I'd take my dd to school and pick her up (or put her into an after school care who would do this for me).
I'd not allow her any money for school. Packed lunches all the way.
If she wants money for something (magazine etc), I'd give her some but then ask for a receipt to account for the expense.
i'd ground her each time I discovered she was smoking. Give her punishments such as extra chores.
If after three times, she's still doing it, I'd simply not allow her out anymore without my supervision.
If you give in to this, she'll think she owns you. This is a boundary you can't allow her to pass or you'll be opening yourself up for a hell of a lot worse.