If you have an assured shorthold tenancy agreement, you have the right to exclusive possession of the property for the term of your contract. Unless it is for repairs or inspection, you do not need to grant your landlord entry.
In many cases the landlord may need to access the rented property for a multitude of reasons. This could be for a routine electrical inspection or to assess the condition of the property. By law, landlords cannot enter the property without permission. Tenants are entitled to a statutory quiet enjoyment and possession of the property without any disturbance from the landlord.
Landlords must provide written notice at least 24 hours before entry. Tenants may reject the entry if the time is inconvenient and propose an alternative time. The landlord must provide details of who will be entering the property and for what reason. For example, a landlord may request access to do a viewing. If a tenant refuses entry after reasonable notice a landlord may still enter where the landlord has made attempts to negotiate alternative times to visit and explaining the need for the visit e.g. if damage is left it may cause further deterioration or cause injury. There are exceptions to the requirement of notice and this is in the case of an emergency e.g. fire, gas leak, flooding, structural damage and potential violence or criminal activities.