You obviously need to regularise your marriage to have it recognised here before you apply for a spouses visa and I assume you are doing this by an application for certificate of approval.
The criteria for a spouses visa is that you must be able to support and house each other without the need to access public funds.
If you are legal in this country and claiming child tax credits then this will probably be okay, but they may reject the application if you attempt to rely on any increase in those credits that you would receive by virtue of being married to your husband. Do not include these.
Provided you can show there are jobs that you both can do (ie. job advertisements, your respective qualifications) and evidence the money you presently have available then you should meet this criteria assuming you adequately evidence your budgetary requirements for the money available and your current expenses. THey may reject on first instance but you will have leave to appeal and you generally get a fairer hearing of the evidence on appeal.
You should consider instructing a solicitor to act on you r behalf when you make the application.
Provided you can get married without him being deported then the overstay will probably not be fatal to your application.
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