Thank you for this very important question. Many families who are new to homeschooling often have concerns with this issue. The answer to your question is quite simply, yes, your parish church will be responsible for administering the sacraments as they are needed. It is important that you inquire as to parish requirements and introduce yourself to those who will be interfacing with your dear children when the time comes. For the most part many parishes are eager and happy to help parents fulfill the need for sacramental preparation and reception.
Let us pray together a Hail Mary for those dear children who suffer spiritually due to failure upon the part of parents and guardians to introduce them to their Heavenly Father and the One who loves them beyond our human understanding of such a love. Jesus, we ask that You guard them and allow that their parents are awakened to the importance of caring for the spiritual needs of their children. St. Maria Goretti pray for us.
Sending out a prayer,