Change of tenant on AST

Tenancy Types and Management

Hi

We have 2 people on an periodic AST one wants to move out & one wants to stay, they have someone who wants to take the place of the tenant moving out. We are happy for this to happen, not had this before so are are thinking through what we will need to do the following;

1. Credit check & right to rent check on new tenant.
2. If above comes back ok create new tenancy, take new deposit, issue How to rent, copies of Gas, elec, EPC, deposit info.
3. On change over day do inventory check / create new inventory.
4. Refund deposit on original tenancy.

In terms of ending/starting new tenancy does this have to align with the dates on the AST or can we agree with the tenants to end contract mid month, & work out the rent proportionally? If so what is the best way to do this?

Is there anything we have missed?

Thankyou