Phillipa I've not a home visit but I know others have.
The advice I would give is not to rush around tidying up before they come,try and behave as if it is one of your worst days (which it very rarely is when a visit like this is being made!). Make sure that any aids you use are handy and nearby.
Don't rush to put the kettle on and make tea, in fact as this is one of the most difficult things to do sometimes, ask if they want a drink would they mind making it themselves cos today is a not day for you.
Answer any questions as if it is the worst case scenario.
YES I'VE CHANGED, PAIN DOES THAT TO PEOPLE.