If you think you qualify for AA, apply for it, but get Age Uk to help you complete it.
The worst that can happen is that they can turn you down. If you do get turned down, get the appeal form and appeal, make sure you request an appeal in person, not just a paper review.
The review in person, means attending a meeting with a doctor, disability expert and a solicitor. It is not at all court like, you sit round a table and you can take someone with you. It is not accusatory or cross questioning. You will just be asked about what you wrote on the form.
The vast majority of appeals are granted, the Appeal Panel usually know and understand far more about disability than the clerks who make the original decision. I did quite a number when I worked for Age Concern (Now Age UK) and never had an AA appeal rejected.