Good luck! i am sure it will go fine, we were really nervous for our first one for Cookie & Treacy-Bum from Walsall RSPCA.
They are looking to see what environment they will be in, things like cage size, your knowledge on diet, what you'd do on holiday, vet care - that sort of thing. I am sure you will be fine. Let us know how you get on, looking forward to hearing that it is a success for you and Tilly.