IF from another tab?

Hi, I need to update cell E12 with the current period (F5 & P3 & Q3) on the FX tab.

The FX tab updates automatically when the period changes and currently we have to copy and paste it in.

So if we are in June and the base rate is ZAR to pull in cell H21. July pull I21.

Im sure this is easy if someone could explain it as well that be great.
Thanks