Hi Liv,
I'm sorry to hear about your situation. It sounds like you've been through a lot. I'm glad to hear that you're still motivated to pursue your education.
Yes, it is still possible to sit an A Level exam as a private candidate. The deadline to register for exams in the UK is usually in January, but there may be late entry options available. You can find more information on the exam boards' websites.
Here are some of the exam boards that offer A Level Politics:
AQA
Edexcel
Pearson
Once you've chosen an exam board, you'll need to find a centre that will allow you to sit the exams. You can search for centres on the exam boards' websites.
I would recommend contacting the centres directly to find out more about their policies for private candidates.
I know that sitting exams as a private candidate can be daunting, but I'm sure you can do it. You've already shown great strength and resilience by overcoming so much. I wish you all the best in your studies.
If you have any further questions, please don't hesitate to ask.