It may be helpful to write down the many things you have problems with. How you cope with your daily routine, anything special you need to do to get out, problems you may have cooking for yourself - all those sort of things.
The sort of things they look at are your ability to look after yourself. Can you get out OK, if you had to go to the doctor's for example. How far is it, do you get the bus, how far do you have to walk, does someone take you by car, could you get there on your own...
Don't go into massive detail, the person visiting may not have time to go through it all if you do. Simple things like how far you can walk without discomfort. Have a look at some of the questions they ask if you were to claim Disability Living Allowance, as an example - direct.gov.uk/prod_consum_d... and gov.uk/dla-disability-livin... go over the basic points.
Is there someone who can come and be with you when they call, to give you moral support ? They do not need to be answering questions for you or anything, just to sit there and smile, so you're not alone.
The best way to deal with a visit is to tell it like it is. Explain that you need their help and support and would like their assistance to help you find and claim what you are entitled to. Let them give you the options, answer their questions as best you can and don't be afraid of them.
Remember, they know nothing about you so you must tell them of any severe problems and just how they affect you. Don't leave anything out as it can only help your case if they understand what these difficulties are.
That's why I suggested writing things down, so you are sure to tell them and can't forget.