I have no assets, am divorced with a new partner but not remarried & have 2 children under 18.
In the event of my death do the kids automatically go to live with their father (even though he's in special housing as just completed NHS rehab & is not fit to look after them). What happens to my boys?
If you die without making a will your partner will not get any of your estate. It will go to your children. If there is a dispute between your partner and your ex as to who should have the children the courts would resolve the matter by looking at the children's best interests.
OP, as prh47 says, you do need to make a will assuming that you want your partner to inherit.
In the event of a dispute either the children's father, your partner or a member of your family may make an application for a residence order under the Children Act 1989. Whilst that was ongoing, the children may go into care, depending on the circumstances.
You can appoint a guardian in your will but it's important to understand that that appointment isn't binding on the court, in other words although they would take it into account, ultimately the court would make the order it considered in the best interests of the children.
I have a paid for advert over on Classifieds /Small Business titled "5* Will Writing Service Recommended by Mumsnetters" if you're interested. Although it's a fresh advert today, you can see feedback on the link in the ad.
So if I died I would want the younger children to be looked after by adult siblings including one with whom they live but their father is their father and if wanted he has in a sense first priority - given there is nothing wrong with him in terms of competence to care. However your assets (although you have none) can be in trust for the children with someone else you trust such as a sibling looking after them. I know one man whose wife died of cancer and she worried after she died her husband whom she still loved and lived with would take the children out of private schools at some stage so she left her half of the house and savings for the children in trust with her sister and mother as trustee for the money to be used on school fees so her husband cannot touch that at all or be involved in deciding how it is spent.
You must have some assets if you live in a house- if you rent, you will have income presumably? And possessions - a car etc? Furniture? All this would go to your children unless you make a will to say otherwise.
You can appoint trustees etc to look after your estate and put your assets into a trust for the benefit of your children but this is more complicated than just a will.
Go and see a solicitor who knows about wills and trusts.
Dying intestate leaves your assets open for other family members even your children's father to claim. Not only that but you would need to appoint an executor to deal with all the legal formalities after your death such as informing the people such as the bank of your death, paying off bills, making sure any beneficiaries get their inheritance etc.