You might want to try the method HERE to get WU client up and running.
If this is an existing Win7 install (versus a brand new install), you can skip 3125574 and you should already have IE11.
You just need KB3020369 andKB3172605.
Otherwise that full method *ought* to work, if you follow it exactly.
When you get to Step #3, if Windows complains when you try to stop the WU service after setting it to "manual", just reboot (step #4 and very important).
The reboot will stop the service.
You can then proceed with the other steps.
It looks more complicated than it is.
It will only take a few minutes and few reboots.
WU should work normally after that.
(Also, see MS's own official KB article on this, even though their bare bones instructions do not always work without the added steps to temporarily kill the WU service. And this post lists some links to other topics here and at other forums, for more cases where this procedure worked to fix the issue. Here, too.)
Please let us know how it goes, so that we can all learn.