Well…I have just found out that tenants don’t have to get ANY notice to leave if they leave on the day that their contract runs out. Apparently they can just leave the property on the final day and that is that goodbye! They gave no notice at all. Not a courtesy. The contract says two months’. I have the deposit still and have said I will keep it to pay the rent untill I find the new tenants but they are saying no and have got the deposit scheme involved.
Yes this has always been the case. Tenants can leave on the last day of the tenancy without giving any notice. Unless that is you include a clause in the tenancy agreement saying they must give notice. I always put such a clause in my tenancy agreements exactly for avoidance of such cases.
Do not be surprised when the tenancy deposit scheme rules against you!
What about all the tenants with children who are told by their landlord that they have to leave with no notice? 
You have to be aksing asking asking the tenant every month before the end of fix term to renew and asking if they want to renew. That is the sensible way this does not happen to you.