"Dose anyone know when dose samsung fe (bt uk) going to get there one ui 3.0"
The Samsung Galaxy S20 FE 5G in the U.K. on CSC code BTU had Android 11 & UI 3.0 rolled out 23rd December
Check your device's model and CSC code.
Go to... Settings > About phone > Software information > Baseband version (post this) and Service provider software version (post your 3 letter CSC code, see screenshot)
Your model of Samsung Galaxy S20 FE is not the 5G version, (SM-G781B), but is the 4G model, (SM-G780F) and has a U.K. CSC code of BTE.
There have been no Android 11 releases for the U.K. 4G phones, both unbranded and carrier branded, to-date. As for when your CSC code will receive it is anyone's guess but at the pace they are doing their worldwide roll-out, I would estimate 5-10 days.