There is a list of the questions that you are likely to be asked in our ESA/UC Claim guide.
Practically, make sure you are seated comfortably these calls can last a long time.
Have a pen and paper available in case you want to note something.
Make a bullet list of the issues you want to try and cover, you may not have the opportunity to go through them but you can still tick them off as you progress through the call.
A drink, you will be talking a lot.
If possible, put your phone on hands-free. It would be worth your doing a test before the real call so you know how it all works.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems