It is unacceptable (but understandable) that they do not want to pay a months rent just to get it back at the end of the month
But how do you feel about them personally?
Do you feel they will do something on you before they move out
If you are worried about them doing anything untoward, let them know they will be evicted immediately
Is there a time period in the lease in which they can be evicted for non-payment of rent? I usually put in seven days
Believe me if they are planning to leave the country in a matter of weeks they will want somewhere to stay until then, and will/should comply
On the other hand if you are happy with how they are keeping the place and have no other concerns, do a full inspection now and ask for payment of any damages straight away
Then advertise the property for rent today, let them know that since they have not paid the rent, in lieu of deposit, that you understand but that people are going to be looking around in the meantime and for them to keep the place tidy
unfortunately, in a situation like this the PRTB are not going to be able to anything for you
If they move out and are gone back to the UK I cannot see them chasing them for unpaid rent
It is down to as I said above how you feel about the tennants
Being a landlord is like being a employer, you are in control
Unhappy: get them out, keep deposit and rent again
Happy: inspect, advertise and rent again