For those distances, you really don't need gels. Once you get closer to the half marathon distance, it's probably a good idea. When I was strictly a road runner, I didn't realize the value of fueling my body before/during runs. I thought I was amazing because I could do a half marathon without eating before or during the run. I didn't realize, until I became a trail runner, the disservice I was doing to my body and to my runs. A car can't run without gas and a body can't perform, optimally, without fuel either. At the very least, I use a handheld water bottle with electrolyte powder, which is generally about 200 calories per bottle. Ultra runners try to take in about 300 calories per hour. As a road runner, you don't need that many calories, but by taking "some" in, you will be better fueled and will feel better.
This may have been overload for the question, but it's just my opinion and what works for me.