Have your tenant move out into their newly purchased property, leave the house empty and keep the keys until the new tenant moves in.
Or
Refund approximately 3 months rent to allow a new tennant to move in earlier than agreed (see below)
Background facts.
Rent has been paid in full in advance for 6 months (up to end of September)
It's a 12 month contract with agreement we can leave the tenancy at 6 months (September) if we pay the agents Re letting fee (but are responsible for rent until a new tenant is found)
We will complete on our purchase at the end of June and want to move into our new home then. It's not far away so if needed we can keep coming back to check on it etc but I know if it were me, I'd sooner have a new tenant in. It is very expensive. The landlord was a bit of an arse hence us paying 6 month's upfront.
Thought welcome. I hope I've explained it!