jamesy,
There's no need to be concerned about making a claim for child benefit & child tax credit. You just make the claim in your name. You are entitled to it and you are not under any immigration restrictions.
Read this thread again and follow the links.
It's your choice of course to decide how you run your finances but there is no risk to the ILR for your wife.
Anybody here in UK under the old rules will be considered on those right the way to ILR (settlement)
There is no requirement for any savings.
A couple of points to hopefully ease any stress about finances:-
- Firstly, there is no requirement for any applicant using form SET(M) to be employed. It may be that the case the case that the applicant has never worked since arriving in the UK.
- Secondly, the UKBA caseworkers are under instruction not to reject ILR applications solely on financial grounds.
Do you feel that the household income is marginal?