I don't have a CC course nearby to school over and make do with making my own obstacles and like MyBoyPuck suggested I use things on the trail! I always check out the take off and landing sides of logs, ditches, streams etc to make sure they are safe before I just go over/through them.
I practice my water when it is rainy use a trench at the back of our property that I know is safe. If you have access to a dam that would be another good idea too.
Goodluck with your schooling