Another piece of advice. When I teach somebody their solo flight is just that. I usually stay in the pits so the student does it all themselves. Start and tune the motor, taxi out, take off, land, and taxi back. I usually like for them to do 3 complete take offs and landings before they are actually soloed. I don't know if that's how you instructor plans on doing it for you, but you could find out where he will be during your solo. If you are so nervous that you may actually be in danger then ask him to stay close enough to take over in an emergency.

But if you are that nervous then you need some more practice before you solo. You should be nervous, but not to the point that you can't function.

Just my .02 worth