It depends on how close your friend is with regards to price.

The reason i asked about if you are a florist (qualified or experienced) is because a wedding can be very stressful when new to it and if you are not qualified yet, it may be better to ask you tutor to overlook what you are doing if you are a student. you would feel dreadful if you messed up a bouquet for a mate.

I learnt the charges etc at college in the underpinning knowledge. Maybe your tutor could help, again i dont know your situation and would not want to assume.

I would not charge the same for a friend as i would for a customer.

Why dont you get her to pay for the flowers and then charger her an hourly rate of say £15?