The roadside stuff is a lot more forgiving, just be mindful that you can cover a lot of ground, which might overcook the young dude a bit. Just about every major and several smaller roads has a trail in the scrub one side or the other. These aren't marked as part of the "proper" trail network, but they're all part of the Shire's shared-use trail system.Just as a heads up Red Hill's trails are very unforgiving to people learning on a bike. They are steep and techy single track (track is only as wide as 1 rider) with roots, ruts and blown out corners everywhere. Also It's a steep climb back up to the top as well with a climbing track that will be difficult for a beginer to navigate and maintain cadence on the roots.
Definitely give their skills park a good go and make sure you can do everything confidently there before heading to their actual trails (probably be fine on their green trail though).