I resized the windows partiton to the minimun necessary (100G), disabled secure boot and I also remove bitlocker key encryption on windows drive, this allows Ubuntu to see that partition and allow windows to boot with secure boot disabled, without complaning.
This makes everything go easier if you want to keep windows arround on the same disk and dual boot with Ubuntu, you should do this it helps a lot. Even after you disable this, you can re-enable it back, both secure boot and bitlocker key encryption.
Before installing on windows updates resize your windows partition, installing all windows updates will not alow you to gain as much space as possible. After resizing the windows partition to the minimium size you want, install all windows updates, bios and driver updates.
I upgraded all windows updates to the latest version and all drivers to the latest version and upgraded the bios on windows to the latest version before installing Ubuntu, I don't think this makes much differenc…