We have been home visited by RSPCA in the past, the first home check was nerve wracking but I am sure you will be fine
They will be asking things like
What cage do you have?
What will you feed?
Are there any other pets in the house?
What are you planning to bed them on?
Have you got a vet in mind?
Can you afford vet bills?
What will you do when it comes to holidays?
So just think of answers to those type of questions.
Let them know you are part of the forum too...
Hope that helps, please let us know how you get on and good luck!