Sorry you have been getting a hard time here! I think many posters don't home educate.
Are you asking about the legal requirement to remain in education until she's 18? That I can answer.
You have a legal duty to educate her until she finishes "Compulsory School Age", which for her will be the last Friday in June 2021. After that, the duty to remain in education until her 18th birthday rests with her, not you.
This is a legal requirement but it is not enforceable. There are no criminal penalties attached for noncompliance. The door is open for penalties to be introduced fairly easily at a later date, but just now, if she doesn't stay in education, absolutely nothing will happen to her. The only immediate practical consequence is that if she did stay in home education beyond the end of CSA you would remain eligible to claim Child Benefit and Tax Credits for her as a "young person continuing in education" same as if she were at college, which you can do until the day before her 20th birthday. If not, those benefits end in August 2021.
So, you do need to be educating her until June, and later if it is essential that your eligibility for benefits continues. However, there are many ways to do that. It doesn't have to be formal education such as English and maths GCSE. It can be driven by her. This is called "unschooling" or "autonomous education" and is well recognised among home educators. If I were you, I would think in very broad terms about what she actually needs to know in order to be well-equipped for her future, and offer her opportunities to learn those things. See what she wants to do. What does she spend her time doing when she has a choice?
I am sure you are in a better position than I am to know what she'll need, but here are a few examples which might be a starting point:
Cookery and food safety
Baby care
First aid
Finance: interest rates, consumer credit, the tax system, investments
Home maintenance
Consumer rights
Safe internet use
And maybe she has interests such as
Music
Foreign languages
Cultural history
Crafts
Fashion
All of those count as education. If the Local Authority want to know about her education, it is just a matter of explaining your general approach and giving information about what she is learning. You can come here or to another home ed forum if you need help with how to lay it out so it is easy for them to understand. Some LAs have a narrow view of what constitutes education, as their staff often have a school background and no training whatsoever in home education, so you may have to spell it out for them.