Use a combination of condom & a spermacide. Those films are good (together w/something, not alone unless you're ready for the odd 'oops')). If you become regular, then she should go on the pill.
Your first time together should be special. I'd suggest coughing up the dough for a dirty weekend someplace nice. Rent a cabin someplace, or a nice hotel, its doesn't have to be tres expensive, but it should be something you will both relax & enjoy.
A nice sparkling wine & a flower for her (for after) is a cute touch. Make looooove to her Fras & be happy. She wants you, its all good.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh