"If you cannot establish any interest in the property, but you have children, then you may be able to apply on the children's behalf for a share of the property. This application can be made under the Children Act 1989. Orders can be made against your partner. This includes orders to transfer the property from your partner to you as the parent who is caring for the child or children.
The property will be held by you for the benefit of the child / children or transferred to the child / children directly, this can include a transfer of a tenancy. (The children can only hold a property in their name if they are over 18.)
There is one way in which you as part of an unmarried couple might have the same protection in financial disputes as married couples. Under the Law Reform (Miscellaneous Provisions) Act 1970 an engaged couple who separate will have the protection of any law which relates to the property rights of husband and wives. All you need to show is that there was an "agreement to marry" and that this agreement has been broken."
https://www.compactlaw.co.uk/free-legal-information/relationships-family-law/unmarried-couples.html