UK Property Law
Get UK Property Law Questions Answered by Experts
Is she sharing the house with you?
It depends. I suppose you don't have a formal AST agreement?
Do you share a bathroom and kitchen with the other tenants ? Or are you self contained?
You are on a periodic tenancy agreement. The disadvantage of that is that she doesn't have to secure your deposit so the fact that she has not is not helpful.
However, she does have to give you proper notice. That demand a S21 notice on or before the rent date giving you no less than 2 months notice. In fairness, 3 months notice was almost certainly adequate but whether or not the notice she used is sufficient is another matter.
To get you out she would need a possession order although that doesn't seem to be her intention.
To do work while you are there is more complicated. She is entitled to 'reasonable access' which can include remedial work like decorative work. If she is denying you access to rooms that you pay though then you are entitled to a reduction in rent. It may not be enormous but it would be there. The other alternative is to just refuse access but whether she would accept that is another matter.
Can I clarify anything for you?
You will need to let her in for viewings. If you don't she can force entry.
In terms of her moving back in, you cannot stop that. What she cannot do is exclude you without lawful authority.