If I move into a public housing I have to stop being paid rent assistance and start paying for bills it will be discounted obviously but I have to do

You have to weigh up what you are paying now in rent, with what you will pay in public housing.
25% of you current income(without rent assistance) will be the amount you will pay in rent.
You will also need to pay power/water bills. All of your food bill plus everything else you may have taken for granted where you are now.

That doesn't make sense.