Hope that you managed to check out the venue. reading back to the original post, I find myself unsure of the lighting conditions. You say it is an indoor garden but there is also talk of sunlight. Is it a really big green house or something similar?

You also indicated that your girlfriend invited you to this event. Are you covering the entire event or just taking photos of a few people at the event? If covering the event in an official capacity will you be required to carry liability insurance? Is your equipment insured? I have begun to realize that your role was not fully defined and it leads me to more questions.

If you are covering the event what are the client's expectations, quantity quality and delivery time, and do you feel confident in being able to deliver? There will be a lot more time processing images than spent at the event. There was no mention of being paid, only your desire to gain experience and exposure. It could be worthwhile to you to work for free as a step to launching a career, but only if you can meet or exceed expectations.