YOU as a tenant OR a parent don't need to have a smoke alarm in your property by law. Remember that.
A LANDLORD has a LEGAL OBLIGATION to provide one for the tenancy. It is the responsibility of the tenant to make sure that it's working and batteries are tested.
FOR THEIR OWN SAFETY. No legal action can be taken if you don't replace batteries.
There is nothing to stop you getting your own alarm, but you can't be penalised by courts for any reason whatsoever for not having one.
Think about it! :)
You are so caught up in the FOG (fear, obligation and guilt) that these abusive arseholes have created so that they can try to gain power and control over you that you are losing sight of all reason.
S'ok, happens to us all in abusive relationships, but please, take a step back, take a breath and THINK about what the truth really is and what your boundaries are and STICK to them.
The most important word we learn when coming out of dynamics like this is NO.
You think we are all so clever/sorted etc? only cos we have distance, and have faced this same kind of shit in different guises and come through the other side. You are in the middle of it. When we were in the middle of our situations, we couldn't see further than our hands either.