Bloody awful new downstairs neighbour

If she is playing loud music and/or creating deliberate noise after a certain time, then it makes no difference if she owns the place, rents it or is lodging there, she is breaking the law as its classed as anti social behaviour and you are quite within your rights to report her to both your local environmental health department and the police. If she continues, a court order can be made to seize any electronic equipment and prevent her from making any noise between certain hours.

As for works that are needing to be done to a property, it is always a case of buyer beware and if she didn't have a survey conducted prior to buying, then she's an idiot.

I've suffered noisy neighbours in the past, its not fun and YANBU.

Our council will pay repair bills on behalf of owners like her to the factor to allow essential communal work to be done. e.g. roof repairs
The council then registers the debt on the deeds so that the accumulated debt will have to be repaid when the property is sold. You need to find out from your council if they run a similar scheme.
As for the anti social behaviour, report it and keep reporting it. Bullies only get away with it while the victims do nothing. If every neighbour stands up to her you will probably find she will sell up.
Sympathy goes out the window when other lives are affected.

You need to start keeping a diary NOW!!
Record the noises from her flat, preferably on something like a mobile phone so there's a time stamp, and upload it to a computer, or a memory card!
Ask your local council for advice on noise control as they can advise you on how to go about getting someone to help you measure the decibels. Nouse abatement, I think it's called!
Ask your neighbours if they have any complaints about her and if they do they can start diaries, too, and do their own recordings. I'm sure other people are affected, too!!
And good luck.

Good advice above. Don’t accept her behaviour and change your lifestyle. I used to live next to a man who had 11 dogs and went off for weeks at a time, leaving them to someone just to feed them. They would howl and bark 24/7. I wrote a little note to the surrounding properties giving name of council employee who dealt with noise problems. 14 people complained and the council/RSPCA /police came out over Christmas and took the dogs to safety. You don’t have to put up with her. Complain politely and keep complaining (with evidence) until something is done. Good luck and keep us updated please.

She's lucky you are so tolerant.
My friend lived in the same road as a young couple who were give an upstairs flat by the council. Downstairs flat was occupied by a man with severe mental health. He constantly several times a day rang their bell, banged on their door and threated to stab them. The girl was pregnant and terrified to go out. He also stood in the street telling kids he was going to chop them up. Police spoke to him several times but did nothing.

Posted too soon.
One night he started banging on their door and threatening again.
The young lad lost his temper, threw a brick through his window and grabbed him. He smashed his phone and shouted at him but didn't hit him. It went to court and he got community service. The young couple were rehoused as it was gross provocation.
This is often the fault of care in the community or rather the lack of it. Everyone has a breaking point. Report to police OP. Don't let it go too far.

Thanks all! We have just sent a firm and factual email asking her to stop the behaviours which impact on us and been clear we consider it harassment. So far nothing more than a few nasty emails in response, for example, about what horrible people we are and she hates our car (it's the smallest car we can load a mobility scooter into but she thinks it's too big and parks us in) and complaints she can hear our washing machine running - again something we need as we provide care for a young person with a serious medical condition who is also quite exhausted by it all! Trouble is you never know when it will all kick off again. It's interesting to think of it as provocation, that really does sum it up, she stops as soon as we react. That makes me feel like we're being dragged into some really nasty little game of some sort and it's not something we want to do. I keep a diary and all the emails from her, for example one saying that a previous incident was to teach us a lesson (we were in bed about to go to sleep at the time so no idea what it was about). Unfortunately she refuses to meet or speak to anyone in the block and we don't want to scare her by knocking on her door during an incident late at night, so apart from email there's no sensible method of communicating directly. I agree, think the failure of Care in the Community has a lot to answer for as she's making us miserable and it must be quite hard for her as well.

Think about making it more formal and sending a solicitor's letter.

If (and when) she decides to sell, she cannot do so unless she has paid any arrears of service chaeges and the like.

Your lease should contain details of what actions can be taken against a flat owner who does not pay their maintenance charges and this could include legal actions like taking her to a small claims court and if necessary sening in bailiffs.

In the meanwhile follow up all the monitoring measures recommended elsewhere on this thread.

She is clearly not right in the head and that makes it really hard to be reasonable because she probably won’t even ‘get’ it. I think keeping a diary is a good idea because at least it will feel like you are doing something and it might just come in handy if things escalate. Any chance of getting her to play music at designated times rather than half way through the night? We have a strange neighbour and that timetable thing has worked with him. You could maybe run your washing machine at a certain time just to shut her up and say that you have your side of the bargain,too. Just a thought.

Nana8, if we ever get a chance to talk to her that might be a very helpful approach! Thanks. She has so far hurled odd accusations but not been able to clarify what the issues are, eg, after one of her noise 'complaints' (which involved her repeatedly slamming her front door, fracturing the rising main and sending emails telling us this was her revenge for our awful noise) we emailled and asked exactly what, where and when the offending noise was so we might be able to do something about it but so far she has never responded to things like that and refuses to discuss. We wondered if it was the communal door slamming (could be any of 9-10 upstairs residents coming and going plus post and delivery drivers who are buzzed into the hall) as it made no sense in terms of what we were doing (reading quietly in bed) but because we don't know what her problem is we can't do anything. It's very sad but also upsetting as it disturbs a seriously ill person who lives with us. We can't sell up now without declaring it to a buyer, so we may have to move and rent the flat out, just for some peace. Anyway, she's been quiet since we told her to stop harassing us a few days ago, so fingers crossed it lasts for a while.