My first suggestion is to buy her marriage certificate (if you haven't already got it) to determine if she had been married before.
If so there may be descendants of that line.
Then check the GRO Index to find issue of Ethel & Willie Cunningham.
Whether you buy their certificates dictates how accurate any further research could be.
After determining the names of any issue use GRO Index, electoral registers and newspapers for the relevant areas to progress the research.
Other avenues of research may also be open - school registers, NHS records, work records and even the 1939 National Register (but I suggest waiting until the 1939 is online in a year or so as it will be cheaper then).
There are also other sources but the above gives you a start.
Cheers
Guy