Hi Ron well from what you have said looks pretty plain sailing to me providing your land lord will give you a letter saying you can have your missus and kid there the no recourse to public funds bit is only for the first two years and with your net income plus "savings" grant no problem I can see.

If she works that might affect you rent being paid and then theres the council tax as you wont be alone in the flat but doable Go for it and all the best