finally got a date for assessment

after over 3 years i have a date for my assessment in 4 weeks time.  relief and so worried at the same time.  what if i cant explain well enough for them to understand, will i forget what to say,  i mostly communicate via writing so will that be enough.  minds on overdrive now.  also says clinical interview in acia, is that the same as ados cant see much about it online.  asessment is with a senior pychologist and an assistant psychologist.  should i write anything down to take that will take the pressure off a bit.  any help would be appreciated, thanks