Inheritance after a single parent death without will

Its been 5 months since my mother's death,my father is still alive and he recently got married again.my mum had a bank balance of 128 pound which the bank divided among me, my sister,my elder brother and my dad equally.the problem is we have an immovable property,the house where i live at first floor and it consist of same house but with 2 seperate doors.now my dad is creating a lot of problem to give our shares.my dad is telling that he will sell the portion of the house where i live only and also that he is going to divide only this money amoung us siblings which is 2684 pounds , and that he won't give us a single penny more neither will he sell the other portion of the house.And the place where i am living meaning the portion of land and house he is selling is a state land.He had a join account with my mum before...and he is putting pressure only on me to sign my right and is willing to give me 4295 pounds and told me to leave the house after giving him the keys and never to return again claiming any right.please guide me concerning my rights .what should i do.