I am aware of organisations within the Social Housing sector who have included the clause into the tenancy agreement regarding access and if access is denied then procedures for entry including force can start. This is after all other avenues have been explored and this really is the last resort. However, if I can refer you to the HSE Document IND285:
What action is required to gain access to property?
The contract you draw up with the tenant should allow you access for any maintenance or safety check work to be carried out.
You have to take ‘all reasonable steps’ to ensure this work is carried out, and this may involve giving written notice to a tenant requesting access, and explaining the reason. Keep a record of any action, in case a tenant refuses access and you have to demonstrate what steps have been taken. If a tenant continues to refuse access after repeated contacts, you may need to consider proper action through the courts under the terms of the tenants’ contract. However, do not use force to gain entry into the property.
The last sentence is very important. Any arrangements an organisation makes for entry does not included “Force”. However, it is all about gas safety but it would be up to a court to decide whether entry was taken in the tenants and gas safety best interests. I would also get legal advice before deciding on any changes to tenancy agreements which might include entry gained by force.