stepmother vs the children

Hi







I have a stepmother who has never travelled to UK but does have a spouse visa. My dad died recently. There is no will.



I have been told that according to the UK law my stepmother gets all of my dad's estate. Is this true?



If it is true, then what are my options?







Surely, she can't get everything, she has not contributed anything towards my dad's estate. Surely she can not be entitled to everything? It just seems unfair.



Any advice is highly appreciated.







Thanks

stepmother vs the children