It's very unlikely that you can do Textiles at home as your work has to be marked by your Teachers, instead of examiners. They also need to make sure that the work you do is your own. Your only option really is to ask your school if you can do textiles work independently in substitute for Art, so that your teachers can observe you doing the work plus some guidance. Then doing stuff that you can't do at school like sewing at home. Art and Textiles are marked using the exact same criteria so it shouldn't be an issue to get an Art teacher to mark your work. It's just about convincing the school that they can trust you to do the work on your own.