I agree with others that college from September seems to make sense. Here are details of the legal situation:
Until June 2015, your daughter is of "compulsory school age" and must be in full-time education. Home education would be a good idea to cover this period. It is totally straightforward: you do not have to register with anyone, and there are no required subjects. So, she can spend this time focusing on whatever she wants, whether that is settling into British life, working on an art portfolio, or visiting art galleries. Educating children who are of compulsory school age is the parent's legal responsibility. It is unlikely that the Local Authority would take much interest in such a short period of home education, especially as they wouldn't really know what to do with her anyway if you presented her to a school as a Y11 pupil shortly before exams and asked them to educate her for a few months. Chances are she won't even come to their attention and if she does, they'll just say, "er, right, good idea, carry on with it then". If you do have any questions, there is a home ed board here at Mumsnet.
Then until her 18th birthday she must be in education or training. If she is working or volunteering for at least 20 hours a week, this can be part-time education. Otherwise it must be full-time. Home education continues to be an option at this stage. Remaining in education or training at this age becomes the young person's legal responsibility, not the parent's. However, the government has not introduced any criminal sanctions against young people who do not comply.
If your daughter doesn't enjoy the college environment much, then she might want to consider an option other than full-time college attendance.