Congrats on getting your roll, and being happy with your new boat!

Nose plugs are how you keep water out of your nose. They are ubiquitous amongst whitewater boaters, who have to roll all the time.
You can make your own with a wire hangar and a couple of bits of mini-cell foam. I've found commercial ones to be better than the ones I can make, though . . . .
For roll practice, however, a low volume dive mask if probably the best. In any case, whatever you use will be better than nothing - having your nose plugged allows you to hang out underwater, look around at the fish, get comfortable, and take your time perfecting your mechanics. Goggles are great, too.

Have fun!