You will most definitely have to rent something for your wedding. Many venues will offer a limited amount of products but not everything you may need for your special day and not necessarily exactly what you want. Rental companies also have an eye for design so you will be happy to sit down and have a consultation with them (and your wedding planner) to make sure you are getting everything you want and need for your wedding.
Things to consider:
Set up and Tear down times – speak to your venue about this
What your expectations are from a wedding planner