The lesbian stuff is a pretty minor part of the story and mostly skippable. Most of it especially later on will be along the lines of the main character stumbles upon two girls making out and gets invited to join or like a slumber party truth or dare game.Even with all setup of "girls" school, i sincerely hope that lesbian scenes don't overdo or go to the way of the "bisexual slutty love interest" trope that some games has and are reeeally annoying.
That said the "mother" is married to a woman and the relationship with the main character and those two will take some time to develop.