Periodic Tenancy

Possession - Section 8 and Section 21

Hi, My tenant had a AST - which run out in January this year, I carried out an inspection in February, following which a new agreement was drawn up for 6 months, ending in August 2020, however I have not been able to meet up with my tenant, various agreed times, were no shows by tenant, or excuses which are totally made up by tenant. Therefore I think I am right in believing that this tenancy is now a "Periodic Tenancy", is that correct? Also, I have been unable for the same reasons been able to get an EPC certificate issued. I have now received notice from the Shared Regulatory Services (Wales), "Prevention of Damage by Pests Ac 1949, section4. Despite previous letters sent to the tenant, a STATUTORY NOTICE has now been issued. The tenant will not let me in the house (I don't have a key as I lent mine to the tenant as she had lost hers and will not give it back - which I believe I can list as theft, when I send her my next correspondence). What is my position please can you advise. Thank you