Might I say that not signing on is not a good idea at all.
As a single person, presumably living at home, they will get £316.98 per month. But, more than that, they will also get free prescriptions, free NHS dental treatment (if you can actually find an NHS dentist that is), free NHS eye tests and help with the cost of glasses or contact lenses.
Importantly, you are also credited for NI payments. What this means is that these credits count towards your pension eligilibility. I know that your DC won't be thinking about a state pension at the moment but it does help to have these extra NI credits.
The Job Centre can also help with things like paying towards interview clothing if they have nothing suitable or helping with the costs of travelling to an interview.