Council tax benefit

Hi i have just moved to london and im in reciept of sea support group with SDP which gives me £194 a week, also im on PIP high rate care and standard mobility. My question is i was just awarded my housing benefit today, and also the council tax benefit. My weekly council tax works out at £23 a week, they have awarded me £17 a week. That will work out i have to pay £25 a month myself? is that right ? I assumed i would only pay the bare minumin which in my old house was £5 a month. Im band B and its a1 bedroom flat and I live alone. Any help with this would be much appreciated.