Bnb - every person is entitled to a second opinion. Remember that. If you are unhappy with the care this doctor is giving you, request the second opinion. He won't care, it is your legal right.
Also, consultant is the highest level you can go. If you have been seeing the consultant doctor for this, then your second opinion would need to be with another consultant or the head of unit who would most likely be a professor or another consultant.
There is a reason an ob consultant wouldn't want to be taking instructions from a GP. GP are specialists in bits and bobs. Consultants are specialists in their area. Unfortunately a letter from a consultant specializing in ic would probably hold more weight with this consultant. However, remember that the ob has a reputation to uphold, and MUST research information regarding your condition and pregnancy, on order to bring about the safest and best outcome for you and bubba.
Like others have said, you have the right to demand a c section. You have educated yourself on the risks and benefits. The ob has also a right to refuse to perform this c section though, and this would be sorted out well ahead of your delivery date to give you time to see another obstetrician.
I'll bet he didn't know much about ic, and has just needed to read up on it a bit.
Sent from my iPhone using Bub Hub