Accelerated Possession - Are Bailiffs required?

Tenancy Deposits

One of my properties has a Tenant who has advised by text that he wishes to leave and owes 2 months rent. I have sent him a form (At his request)to sign to accept a Check-Out in his abscence and return with the keys about four weeks ago but he has not replied to this The tenancy has just reached the end of its initial term and I have a S21 in place (Issued at the start of the Tenancy)and a secured deposit The Tenant does not appear to have been living in the property for about 6 to 8 weeks as there is bedding thrown on the floor, the wardrobes have been emptied and most of his clothes have been removed (A few are in a pile on the spare bed), he has removed his television and most (But not all) of his other belongings.

I would like to just enter the property and change the locks (I have a new tenant ready to occupy)but I think that I am correct in assuming this would be illegal eviction or would his text notifications allow me to do this despite not receiving the keys.

If I must apply to the courts, I intend to use the accelerated possession procedure and worry about the rent later. If I receive the Order and there is still no response (He is not there, remember)will I still need to use Bailiffs to recover an empty property?