How does this affect me as somebody who builds their own computers for personal use? Does this only affect vendor sourced desktops i.e. HP, dell etc ?
It has absolutely no security soundness. It may protect you against evil maid attack. But even so, less than decent fs encryption.
It's nothing more than a ploy to help Microsoft, and Ubuntu and RH are falling for the sole reason of having too much money.
It's like ssl certificates for bios. Burn it.