Hiya-
First of all I'm really sorry that you're regarding this experience with such fear when it shoudl be a happy and wonderful time for you. Many women find natural birth empowering and wonderful, but many do not. Health professionals should be sensitive to women's needs as every woman is an individual with individual perceptions.
Most hospitals, if you turned up in labour, would attempt to accommodate you for immediate LSCS as you have one booked. As mentioned above this may not always happen- emergencies sometimes take precedence.
If you thought you were labouring before 37 weeks it might be wise to go to the hospital as soon as possible if you feel you're going in to labour as this is considered pre-term and there are certain implications with performing a caesarean section prematurely (the baby's lungs are at risk during an elective caesarean section anyway as the lack of contractions and descent through the birth canal does not remove the excess fluid- it is quite common for a baby to require extra care and attention for respiratory distress). This is particularly pronounced before 38 weeks (even though term is considered from 37 weeks onwards).
I know you say you ould prefer not to have a VE but in this case it might be wise to permit at least one internal examination if you feel you are labouring prematurely- there are other ways a professional can assess labour through touch and feel, assessment of behaviour and other observational signs (though a CTG monitor of the baby's heart-rate is not an accurate depiction of whether or not you are having contractions- you are the best person to tell them that) these are not always evident in early labour, and as you say you are afraid of progressing quickly.
An induced birth is very different to labouring spontaneously- it can progress faster as your body and baby have decided that now is the right time for the baby to arrive. You are not being forced by an artificial hormone. It may also not be as intense straight away- your body builds up natural painkillers in nomral labour that help you cope. I therefore agree with the advice above- if you believe you are labouring, it is a good idea to go to be assessed sooner rather than later, but it they may be reluctant to submit to your request fo LSCS without an examination first, particularly if you're classed as premature. In hospital environments doctors and midwives use internal examinations as a key feature of labour progress as this is a given in those having medically managed labour and births (as their behaviour is not always the same as those labouring physiologically).
Sorry, I feel I'm rambling a little!
It may be worth putting a birth plan together stating your choices and what you would prefer to happen in certain eventualities. Labour and birth is unpredictable, and it is better to approach it with fluid concepts, but at the same time if you are very anxious it would be nice to have something written to hand to your care-giver so you do not have to articulate all of your choices when you're trying to concentrate on keeping it together with contractions.
I know you are 35/36 weeks now but have you considered any alternative forms of relaxation for birth preparation- natal hypnotherapy or hypnobirthing? It is approached often with a lot of skepticism but the principles of hypnotherapy can really assist with anxiety. Hypnobirthing courses are not cheap but do involve partner training, but natal hypnotherapy do offer reasonably priced CD's/DVD's, including one on the experience of caesarean section, for you to listen to in your own time.
There will always be that element of unpredictability as your birth is effectively is someone else's hands- and those hands are often busy, short-staffed, and prioritising elsewhere. My advice would be to ring early, stay calm, and communicate your choices as clearly as you can.
I hope things go well for you, and that the birth of your new baby is as positive as possible xx