Most Landlords would make arrangements to visit the property every 3 months (in a 6 month tenancy agreement) or 6 months (in a 12 month tenancy agreement) to ensure that the Tenant is happy and that you are happy because they are looking after your property.
This is a simple 30 minute meeting and if you take a copy of your Inventory and Schedule of condition with you, there will be no ambiguities between you and your Tenant.
You will need to send a letter in writing to your Tenant giving them at least 24 written notice that you would like to enter the property for an inspection. For the sake of harmony, we would suggest that you give your Tenants at least a week before showing up for the property inspection.
It is important to be clear about what your visit will entail. Landlords do not have the right to comment on a Tenant lifestyle unless it is causing damage or potential damage to the property.
A sink full of washing up or clothes on the floor will have no impact on the property after the Tenant has left. On the other hand a fire door that has been propped open or a smoke alarm that has been disabled is not only dangerous for the property but is also dangerous for the Tenants and their visitors and this needs to be addressed.
No one likes being told how to live and, despite the fact that the Landlord owns the property, while it is Tenanted the Landlord has given Possession to the Tenant and it is his home, Landlords must respect that when carrying out a property inspection.