This sounds rather suspicious
Is she going to steal the white goods ?
Do a deed of surrender
Do it legally so you are covered
It’s £50 plus vat from a solicitor and they will tell you the procedure
You can keep the rent and the deposit as terms of the surrender
You have spent a lot of money for this tenancy and gone through the headache for nothing
Legally she has committed to the AST so she is bound for the duration so keeping a month and the deposit you are doing them a favour