You could probably use the time more effectively training on your own. Your training needs to be geared to your requirements, rather than those of the more experienced riders around you.
However, it depends how long you are hanging with them before you simply disappear out the back. What you describe sounds like an extended period of interval training, and being in the group probably makes you push yourself a bit harder than you would if you were alone. Do you feel you're nearly there, that in a week or two you'll be more comfortable in the bunch? If so I'd stick with it. Otherwise I'd train alone, including one hard intervals session in my weekly training, until I was a bit stronger.