If it helps I dont think anyone ever feels truly prepared, I have done it once before but still wonder how Im going to manage.
I know first time round I was not scared about the actual labour as I had done a lot of reading first so I knew about the differnt stages of labour and what means what etc, so its wasnt all just stepping out into the void, TBH when it all happens you just go with it all and its really not as scarey as you think, its more before hand a fear of the unknown. So its certainly work preparing yourself as much as possible, reading about labour, and pain relief, birthing positions, talking to your OH so he understands whats going to happen and what you expect from him etc.
As for looking after the newborn, this was the scariest bit for me, as Im the baby of the family Ihad no prior experience of children, or babies, and had never even help one. I was scared I wouldnt know how to feed or change them properly or hold them right etc, I had no clue! but its amazing how much just comes naturally, it really is instinctive.
Dont worry the way your feeling is normal, but it really will work out fine.