i was you 18 months ago, absolutely petrified of giving birth. at 42 weeks i was taken in for induction and was still terrified. A midwife on the ward told me that being nervous was holding me back and preventing labour. I spent the next 2 days on all fours until finally labour was started by the midwife breaking my waters.
After the waters broke i can honestly say that all fear went out of the window, your body takes over and theres no time to stop and think about whats happening.
Speak to your midwife and partner about what you want to happen in your ideal birth plan.
As Linneylou said, a water birth can be great. It does mean that you cant have an epidural though but can have gas and air. I wasnt allowed a water birth because i was overdue by so much but I got into a normal bath at 8pm after waters went (2cms dilated) and by the time i got out at 11pm id made it to 7cms with no pain relief.
Have you tried taking raspberry leaf tablets or tea? These are meant to prepare the cervix ready for birth and supposedly ease labour. Perineal massage cal also help to reduce risk of tearing.
Are you a member of a birth board? I recommend ivillage boards as you can join a group of mums all due in the same month. Many will have the same worries and fears and theres nothing to stop you asking on other boards for advice either. heres mums due december 06 board
http://messageboards.ivillage.co.uk/iv-ukpbdec 06
as has been said, all births are different, best to speak all your worries through with others and decide what youd like to happen but be prepared for any changes.