I live near you, and the closest trail system is the Wilderness Trials, they consist of Flatwoods, Trout Creek, and Morris Bridge parks. There is and entrance to Flatwoods on Bruce B Downs Blvd. next to Chili's and South of Hunter's Green, and Morris Bridge road south of Cross Creek Blvd. The Trout Creek entrance is on the Northeast side of the intersection of Fletcher and I-75. There are three entrances to the Morris Bridge section. There is one right across the street from the Trout Creek entrance, this is the one that we call "The whole in the Fence". There are two other entrances up further on Morris Bridge Road, just before the road goes over the Hillsborough river.
There are between 25 and 30 miles of trial. Most of it is very flat, and really good for someone who is just getting started.
I live in Grand Oaks and it typically doesn't take much more than about 10-15 minutes to get to "The whole in the fence", so it is very convienant.