Fasterlaster,
Your Honesty is commendable, but as an instructor, and I think most instructors will agree that you will not be sent up solo before you are ready. IMHO you fear is to do with the unknown and what your imagination puts into your head, get over this by making sure you are well prepared for every flight lesson and know exactly what is expected of you and you will feel more confident, dont just tip up to a lesson and say "what are we going to do today" find out after your last lesson and prepare for the next. Most training aeroplanes are extremely forgiving, and dont just fall out of the sky at the first mistake. Just prepare properly and go through all your checks untill you know them pat. It will make you alot more confident and you will enjoy your lessons more, this in turn will give you the "can do" attitude.
Good luck and keep us posted