My wee seven year old girl has been diagnosed with leukaemia?

and my partner and I have recently separated, we also have a four year old wee girl. Since the diagnosis, I have had to give up work in order to either stay with my seven year old in hospital when she receives chemo/needs treatment for infections, or stay at home to look after my 4 year old. My ex gets DLA, Mobility Allowance (I drive us to the hospital) and large amounts of cash from various cancer charities whilst I only get Job Seekers Allowance. I have written to these charities asking for some financial help but have not even had an acknowledgement of my emails. I am now in a position where I cannot help my children due to severe financial difficulties. Does anyone know how I can get help in order to help my children? I am male.