They will probably just be doing an inspection of the current state to make sure there are no major issues (like holes in walls, stains on carpets, general filth). I know it doesn't help now, but in future just know that they will probably be fine with the house looking "lived in" (I.E. not a sparkling shower/oven) as long as it doesn't look like you've got mold from lack of ventilation or your cat ripping up the carpets/causing issues.
We have been through this before on another thread. That may be what an inspection is in the US, but that is not the case in England and landlords should know the laws of the business they have entered.
As I also said on there, the inspection is only to see what repairs the landord must do, not to see how the tenants live. They don't have to clean and if they want to leave their skid marked underwear around, have a loo that isn't flushed, cook cabbage just before the inspection etc then that is fine as a landlord cannot tell a tenant how to live, because every tenant "has the right of quiet enjoyment of their home".
Under English Housing law, they don''t even have to let the landlord have an inspection, but they then can't complain to the council that the landlord is not carrying out his/hers repairs, if they have not let the landlord look at the repairs.
The only requirement is that they give the property back in the same condition it was given in, less fair wear and tear. They don't have to clean their home at all during the entire tenancy, if they don't want to. They only have to clean it to the standard it was given in, when they move on.
And as I also said on the other thread, gone are the days of the landlords keeping what they like from the deposit as that was stopped due the rise of the "me too, buy to let" landlords, who failed to learn the Housing laws. That happened about 2007 I think? ATM, most professional landlords are worried that these new type of landlords will bring in registration of landlords in England, as Wales has just had to do.
Hassle your tenant, and it is you who have committed the crime.