As others have said you should be able to claim AA, it can be quite a hard form to fill in for a PWD as they don't fit the boxes so getting help from local AGE UK CAB or similar is often recommended.
My mum was clearly self funding, so I would have got on with finding carers if she hadn't gone into sheltered extra care (long story but her house was uninhabitable - so I had to find somewhere else) - I considered sheltered and also just a flat /bungalow - but realised I would be having to do everything so I just wouldn't have the time.
If your mum is self funding (assets not including house above £23k ish in England- different rules elsewhere I think) you could try getting a 'cleaner' in who is actually someone to keep her company for a couple of hours a day. Your mum seems frightened in her own house.
You need to consider how much you are prepared to do, as the more you do the more it will need, this is the nature of dementia.
It isn't just about the needs of the PWD but your life as well, and things should be looked at as a whole when you determine how much time you can spend supporting your mum. I had 2 young children at the time so it was bleedin obvious I couldn't really do much hands on.
If you are not self funding you will have to beat a path to the local social services for support, which as there seem no direct care needs might not be forthcoming, although they might help with daycare places, which might work for your mum when she is anxious alone.
At the stage your mum is at, if she is prepared to move sheltered extra care might work, as there are activities but you are still in your own flat. My mum was clearly more settled and less anxious in her flat being aware there were people on hand, and with the day to day anxiety of 'what should I be doing now' removed.