Thanks for all your advice guys!! Yes, we did get child benefit (about £12 a week), but, we had to pay for a bus pass, school meals, uniform etc for her, and wasn't eligable for anymore benefits!! My niece is now 19 and is entitled to housing benefits, but because we are family, the council have stated that we can't class her as a lodger, therefore, are unable to get the housing benefit for her!!
We did put her in a hostel a few weeks ago (things got too much), in the hope she would become a priority to the council, but they said she could be there upto a year and then she wouldn't get a say in where she was housed - so we took her back after 2 days (felt too guilty)!! So back to square one!! As my son is not yet been diagnosed yet with asperegers (I've heard it can take years) - I'm a little reluctant to apply for DLA until then! Although, I must say, I am 99.9% sure that he will be diagnosed with the disorder!
Well, the cheque was there when I got home (£188) - so that is in the process of being cleared in the bank! I've also been told our creditors date - 3rd september - yikes!! Really nervous, just because if it's not accepted, what are we going to do????