L'oreal Feria to fix my copper yellow blonde hair?

My hair is naturally golden blonde and being out in the sun has turned it coppery yellow blonde... it looks terrible on me. Towards the end of the summer in August, I plan on dying my hair medium brown (Havana brown #50 from L'oreal Feria) before I go back to college. What do you think will happen once the medium brown starts fading? It's a natural color, not warm or cool. And please don't tell me to get my hair done professionally... I'm a college student, I barely have enough money for rent. Thanks!