Studying A-Levels on my own..?

I was predicted A*AA and got that at AS but because of health reasons got CCD in my final exams. I am wanting to resit, but after reading reviews of online courses they seem mediocre at best and downright scams at worst... Does anyone think it would be possible to study A-Levels from home without enrolling in a course ? I am thinking about redoing biology and eng lit so I will be familiar with the content of those already, but want to do a completely new subject for the third one. Advice..?

You can absolutely do this. Loads of people do so every year. Just make sure that all the necessary resources are available to you - especially if you're doing a completely new A level. This could be text books, past papers, web sites, you tube videos, etc.

You'll need to register with an exam centre (normally a school or college) to actually sit the exams. You can find a list here.

Also check the "private candidates" page on your exam board's web site for lots of other useful information, including how to register with the exam board directly.