The Glock 27 is a difficult shooting handgun for "newbies". Due to the light weight and compact size, it takes some practice to become proficient. With that said, be sure that you're able to have adequate time on the range and have a good supply of ammo.
We have discussed the ammo issue on several threads. The common load for LE and SD use is 165gr. Some argue that a heavier bullet will be better, but in my shooting experience (have 2 Glock 27 pistols), the 165 grain has been the most consistant in performance. It's a good balance in bullet weight and energy transfer into the target. Many LE agencies use Speer Gold Dot, Winchester Ranger T, Remington Golden Sabre, or Federal Tactical HST ammunition. There are many choices out there. Shoot all of 'um and see which one you like best. I like the Speer Gold Dot ammuniton. It's more important to be sure that your ammo will consistantly feed when you need it to.
Spend a lot of time on the range shooting target ammo. Once you're confident in your skills with the target ammo, shoot a couple boxes of your SD ammo. You need to do this to ensure that the ammo will perform as expected when it counts the most.
Welcome to USA Carry. Happy shooting, and be safe!