Yes to logging the aggression with the non emergency police. I had to do this with my XH. The police came round and were very good about it, they did a risk assessment - asked me lots of questions. I your friends husband has already been violent she will be a high risk.Thepolice told me that having logged accomplaint any future calls byme about him would be treated as a priority and they would come straight away if I thought I was in any danger. They also gave me number sof local women;s aid groups etc.
they also gave me alist of what to put in an emergency bag - and this is something it might be a good idea for you rfriend to do. get her passport, NI number, birth cert etc etc - all the vital documents and those of her children if she has any and have them in a bag all in one place so that if she has to leave in a hurry she can grab all her vital info. And obviously keep it hidden where he can;t find it or give it to a friend for safe keeping.
She can get an hours free legal advice form a solicitor - she needs to look up which one;s do this. She can also more free legal advice from citizens advice - they usually have a day when they have a legal person and you go and queue up - it can be along wait, but its free and they will guide her in the right direction.
From the info you have given - is she wanting to file for divorce against him? It will cost money, but you don't necessarily have to got through court, and if there is evidence that he is being violent he may want to avoid going to court and be prepared to settle outside of a court appearance. It will still cost money but not nearly as much.
As an idea of costs - my divorce - with a fair amount of arguing the toss from XH and therefore not a straight forward one - cost £5500. I asked for and was awarded costs - so XH has had to repay me this money.
I think the problem with women who are intimdated is that believe what their husbands say. He may want the hosue - that doesn;t mean he has any chance of being awarded the hosue (in fact it would probably at least be split equally, if not be awarded in her favour if they have children) he may not want to listen to a court order but if he doesn;t he could go to prison - you have to sign something saying you understand if you flout the court order this is possible. So I think she definitely needs to get legal advice so she is armed with facts.
if she goes for the freee hour (and citizens advice will tell her which local family law solicitors will do this) then she needs to write down all her questions beforehand and take in a notebook and write down all the info. It can help to have someone with you as an extra pair of ears.
Anyway - good luck to her, it is a shitty situation to be in and hope she can escape from it asap. I found the police great - really reassuring about me keeping safe, and when I did have to call them out again at a later date they were here straight away and dealt with him.