Do I need a deed of surrender?

Possession - Section 8 and Section 21

Have served my tenant with a S21 notice, expired 31 March. Tenant is generally uncommunicative generally sporadic phone calls & texts. Tenant has acknowedged receipt of S21 (by text), tenant has secured other accommodation and indicated a (degree of) willingness to leave. I would prefer to avoid court unless absolutely necessary, we have a provisional arrangement to meet to handover the property. Tenant proposes leaving some belongings which Tenant can't move, I can live with this and will leave them at the property.

Do I need a deed of surrender to accept the property back without the court order or will a letter signed by the tennant suffice? I can have a witness with me on the day, or could recording proceedings if required.

I propose to have 2 copies of a document on which we will record what furniture she has left and that I have agreed to this and will not look to charge her for removal etc. I thought if we both signed this and kept a copy it would suffice as proof to avoid comebacks later.

If a deed of surrender is required is there a template available?