Are you living in England or Wales? In which case, the intestacy rules will apply. In which case the spouse inherits everything up to �250k ("the statutory legacy") and personal possessions. Spouse has the right to elect to take matrimonial home instead of statutory legacy if worth less than that or they can make up the difference.
Of anything left, half goes to the children on attaining 18. The other half is invested for the widow during her life and she is entitled to the income and on her death to the children absolutely.