I work for an estate agent 1 day a week, and they do inventory's on all empty property (if the landlord asks them to) so they are done on unfurnished property. They take pictures of every room, the inside of the oven, any existing marks on the walls or flooring, the garden, sheds, garage, anything and everything.
That way, it can be proven what damage a tenant has done, and what was already there. It protects both parties.
The Landlord must provide you with certain things when you move in , being :
Energy Performance Certificate
Government How to Rent guide
Deposit Protection certificate
They must have a smoke detector on every floor and carbon monoxide detectors in rooms with coal or wood fires.
You cannot move into a property if it is unfit for habitation, and it is the LL's responsibility to clear it and clean it between each tenant.
Take photos of everything, ask him to rectify everything that is wrong, including the window, for security reasons, and he should also pay for the cost of paint if painting is definitely required.
If you have already signed a tenancy agreement and are now unsure about moving in, please get advice from Shelter about how to proceed.