Childminder of 18 years expereince here.
What's the problem with the inspector checking out your rooms? If the children are to be allowed to use them, the inspector has to be satisfied about cleanliness and safety. They are not looking to see if they are tidy or rummage through your personal possessions!
If you don't intemd to use up[stairs for minding, thern they won't go upstairs, but if you only have an upstaires tpilet they will inspect that and any sleeping are for children that is upstairs.
They will check, sockets, leads, curtain pulls, cupboard catches,window locks, door locks, safety catch on washing machine and tumble drier etc.just to name a few
You should have the booklet preparing for an ofsted visit, it can be downloaded from the Ofsted site.
Just follow the National Standards gudelines, all the info on watch they will ask to see and look at is in there.
Good luck