Is it permissible to attend Fiqh and Aqeedah lessons and Quran memorization circles without the father's permission, even with the mother's knowledge and consent, and is this considered an act of disobedience?

If your attendance at knowledge circles does not result in harm to your religion or worldly affairs, then there is no impediment to it without your father's knowledge, and by doing so, you are not being disobedient to him. Sheikh Ibn Baz was asked about a girl going out without her father's knowledge for da'wah (preaching), visiting the sick, and doing good deeds. He replied that it is permissible for her to go out for these purposes with modesty, chastity, concealment, and hijab, as long as her going out does not pose a danger that would necessitate her father's permission.