Anyone know how to get proper ultrawidescreen support ?

try the widescreen fix from the fallout london downgrader mod page
nexusmods.com/fallout4london/mods

Will do thank you

Found another solution
My monitors aspect ratio is 32:10 3480x1200
Edit Documents\My Games\Fallout4\Fallout4Prefs.ini
change the lines iSize H=1200 and iSize W=3840 to whatever your resolution is
run the game alt tab out (not sure if this bit is needed, may work if you run it before fallout) run Flawless Widescreen
load the fallout 4 settings change the fov to whatever you want alt tab back to fallout
https://www.flawlesswidescreen.org