How to download factory version of Android on Samsung Galaxy A300FU

I have a Samsung Galaxy A300FU UK Version which has come from EE Network. I wanted to know how i can download the factory version of Android Lollipop because Lollipop has not arrived yet on the EE network. I have also unlocked my device so i can use it on any network. Also to download and install with odin, what would be the process of doing that and would i need to root my device. Also would it affect my warranty.
Device is currently running on Android 4.4 KitKat. Sim-Free versions have already been updated however some carrier variants have not. I also did not want the carrier bloatware.
Many Thanks!!!