We stayed there last year in my uncle's place. I would say it is a half mile, at most, from the
WalMart. The entrance to Glenbrook is right at the intersection of County Road 424 and 27; 424 runs to the west from 27, and Glenbrook is just to the east. There is a light there, making the left turn onto southbound 27, towards 192, simple.
Edited to add: most maps don't have glenbrook added yet, but mapsonus.com does---you'll get a good idea there.