Yes, a duty - which is washy and consists of telling you to stay until your tenancy is legally ended either by yourself or by a Bailiff - which are the only two ways a tenancy can be legally ended. So yes, it is the law.
Perhaps you read up on that, rather than what councils should and shouldn’t do, especially as each one varies wildly, and it’s your job as a landlord to understand how the contract you signed can and cannot be broken. Unless you fancy a massive fine for breaking the law and possible jail time for harassment of your tenants, should you try and force them out illegally.
Tenants are sick of landlords bullshit, most don’t know even the basic laws and think we should lick their feet because they “gave us a home” - bore off, I’ve paid off huge chunks of other peoples mortgages my entire life, they mostly resent spending even a penny on repairs - and that’s why the Gov is changing things.
Thank the Scumlords, ill educated on even the basic laws, allowing people to live in slums and charging extortionate amounts for it.
I was in the top priority band, but I couldn’t make them give me what they hadn’t got - permanent or temporary housing is rammed and hotel hopping was all they could offer, despite my children’s medical teams losing their shit about that.