Hi
Anyone can apply for PIP. The only conditions are that you must be resident and present in the UK and meet their qualifying period - ie your condition has been present for at least 3mnths and will likely continue for at least 9 months.
However PIP isn't proving you have a disability, it is showing the affect that disability has on your life - dressing and undressing, cooking, budgeting, following journeys, managing medication, moving around etc etc. Worth having a read online and considering if you meet those
You may well struggle when it comes to evidence however. A lot of focus is put on evidence such as drs letters , prescriptions etc. In my experience working in the system, people who struggle to provide medical evidence struggle to get awarded at new claim or recon. That's not to say you won't, just that it might make the process trickier 😀
Also I feel like I need to say this about the assessment, as you seem quite nervous and expecting it to be awful. That's understandable given the media, and the fact that they do make mistakes. At the same time they're not all horrible or incompetent and yours might be really nice. It's hard, but definitely a good idea to try and keep a positive attitude towards it. Only because worrying will do nothing, and if you keep calm and look after yourself, If things go badly, you'll be better placed to fight. Also please don't worry that you'll have to get naked - that doesn't happen in routine assessments 😀
Have a look through the descriptors and see if they apply to you. If so, give the new claim line a call. It's very busy on a Friday or Monday so perhaps Tuesday is best xx