download a fresh ubuntu 18.04.1 there was a bug for some intel boards. also I find it easier to install with the nomodset option for some nvidia cards then after install rub the addl hardware to install Nvidia drivers. since the error listed nouveau that should take care of any issues
If you boot ubuntu from a livecd (or USB stick), right after the bios
splash screen you will get a purple screen with a keyboard logo at the
bottom:
Press any key at that moment to access a menu.
If you press the F6 key, a menu at the bottom will open allowing you to
set kernel options with the space bar or enter key. You can close the
menu with escape key and resume booting
If you need to add kernel options not provided by the F6 menu, you can just type them in at the end of the boot options line.
Installfest is Saturday