To answer this question; you need your contract and inventory, signed when you started your tenancy at the property. In there, it will detail what is expected of you when leaving. For example, you must check that all the items in the inventory are still present, and undamaged.
You must leave the property in the same condition in which you receive it. General wear and tear is acceptable, but damage must be repaired; if you do not do it, your landlord will and take payment for it from your tenancy deposit.
Consider that when you received the property, it will have been clean. So, you must leave it in the same condition; this includes windows (inside and out), the garden is appropriate for the time of year, appliances provided by the landlord and any other furniture within the property. Again, if you do not clean it (or do not clean to a satisfactory standard), the landlord will charge you for having it done professionally.
What qualifies as landlord harassment?