I'm just starting too, and I put a bashring on yesterday. They are VERY necessary. My regular chainrings only lasted a few rides and now are completely unusable because they're warped like a half inch and have few teeth left. Definitely get one.
Most beginner courses are designed so that a stock MTB with large ring can clear everything. I have never hit my bash ring on anything in a beginner comp. The last one I did a guy on a stock MTB did clip a rock with his but he was running a 24-34 set up on his crank. You have that tiny freewheel on there so I would not thing you would have any problems with clearence.