Default [Q] P5100 flashing stock using BTU, but do i need to select firmware for CSC?

Hi everyone,
I have an O2 UK branded Galaxy Tab 2 P5100 and I was thinking of flashing the BTU firmware from sammobile. I have never done any flashing in my life before and I'm sure there are many guides out there that can help but I just want to know if when flashing using odin do I need to put the firmware file in both PDA/AP and CSC box?

Many thanks,

Tarek