Tenant has blocked communication

Possession - Section 8 and Section 21

With interest and service charge rises we need to sell our rental apartments so I issued a Section 21 to one of our tenants (rolling Periodic - AST) last March (2023) giving three months notice. She told me the council had advised her not to leave as she would be making herself intentionally homeless. This tenant has children - one with a medical complaint - so I would have thought she would get preferential treatment for council housing. The council say they have no record of the tenant either complaining or applying for housing. 

At this point she stopped paying her (below market value) rent.

Just after we'd served the S21 my husband was diagnosed with bowel cancer and had a massive operation including a splenectomy and chemo for months so my time was dedicated to him and also my mother has Alzheimer's and I was looking after her.

The good news was I found that the tenant was in receipt of Universal Credit so, as she was two months in arrears, I was able to apply for an MPTL (Managed Payment to Landlord) which to my surprise was put in place immediately and Universal Credit started paying her rent directly to me. As the rent was being paid and I had other things to prioritise, I let the Section 21 lapse. 

This tenant has caused much damage to our beautiful apartment and keeps the windows, vents and curtains closed to cultivate mould. The tenant has never complained about anything in the flat although at our last inspection in the beginning of 2023 the bath was hanging off the wall with the shower water leaking into the garage below. We repaired this but since then she has blocked our phone numbers and emails and will not answer the door to us. I have hand delivered many letters asking for her co-operation but have heard nothing from her. I know she is in a lot of debt as she'd discarded a British Gas bill for over £3,000 in the communal hallway along with other letters threatening visits from bailiffs. She has had installed pay as you go meters so I have no idea how she could wrack up such a large bill. 

December, with no notice, the rent payment did not go into my account. Universal Credit will not speak to me (Data Protection) to explain why they have stopped the payments. The only thing they would tell me was that the rent payments were still 'live' and that the tenant cannot cancel these payments but they would not say why the payments had stopped or if they are going to be re-instated.   

The Landlords Gas Safety Certificate is due in days and I don't know what to do as we cannot serve either a S21 or S8 if we don't have the relevant paperwork/certification. I've been told I should apply for an emergency injunction to gain entrance to the apartment.

Would it help my case if I ask the LA to do an inspection because at least I may then be able to get in to do repairs?

Any advice would be gratefully received.

At seventy years of age I can do without this stress.