I've not tried this range, but there's a shop in Edinburgh I have tried a few from and they are superb. As long as you have the cap on underneath, it shouldn't fall off, look wonky etc. I just hope on QVC they are going to sell the wigs with the caps and show you the correct way to put them on (ie, bend over holding the front of the wig at the front of your hairline and pull the wig over your head, stand up and re-arrange until you are happy with it) and how to adjust them so they fit properly.
Wigs are perfect for me as I am the very same, can't handle having long hair all the time but would like it for the odd night. I am also about to get mine chopped into a crop, so it will be way too short for extensions.