I'm not familiar with this particular version, but if you have a good instructor, there is ZERO reason to be concerned. Yogis are (or at least, should be) well versed in modifications for people who can't do all poses perfectly. NONE of us start out being able to fold ourselves in half, not without some serious genetic blessing.
I have NEVER been able to touch my toes; not even as a slim teenager. Flexibility is not about weight.
There's nothing to be afraid of. Talk to the teacher ahead of time mention your concerns, and let him or her know you have concerns and are a little afraid. I bet you money that the teacher will gladly explain everything and set your mind at rest.
Nothing ventured, nothing gained. Go to the next class, and let us know how it goes!
Writer, mother, wife, and breadwinner. I love to run, but running doesn't love me, so I'm switching to my low-impact bike.
I'm not pregnant, just fat: My blog. fatnotpregnant.blogspot.com/
| current weight: 190.6