Advice from CAB
Married partners and civil partners
Married partners or civil partners inherit under the rules of intestacy only if they are actually married or in a civil partnership at the time of death. So if you are divorced or if your civil partnership has been legally ended, you can?t inherit under the rules of intestacy. But partners who separated informally can still inherit under the rules of intestacy.
If there are surviving children, grandchildren or great grandchildren of the person who died and the estate is valued at more than £250,000, the partner will inherit:
all the personal property and belongings of the person who has died, and
the first £250,000 of the estate, and
a life interest in half of the remaining estate. This means that if you are entitled to the life interest, you cannot get rid of or spend that part of the estate. You can, however, have the benefit of it during your lifetime.
More here www.adviceguide.org.uk/wales/relationships_w/relationships_death_and_wills_e/who_can_inherit_if_there_is_no_will___the_rules_of_intestacy.htm