Autistic and considering declaring myself unfit for work on Universal Credit

Looking for some advice on how to do this, sturggle with communication at times and the whole process seems rather intimidating, know I'd need to get a fit note from the GP to get the ball rolling but unsure what I'd even say to them in regards to how my autism affects my ability to work and also having similar troubles figuring out how to explain this to the job centre too, any advice from others who've been through the process would be much appreciated. Just feeling so overwhelmed even thinking about it to be honest