I don't think (but may well be wrong...) that maternal preference alone is considered a reason to have a section (in the absence of some sort of medical reason). But you might find that your consultant is sympathetic and if he/she doesn't agree the NICE Guidelines say they are supposed to refer you for a second opinion. I do sympathise - I am sure it would be hard to get your head around having a section and then to have to get back into a vaginal delivery headspace.
Something that might not hurt is to make sure you are aware of the risks of section in advance of speaking to the consultant. If you do end up essentially asking for an elective without medical reason it might help strengthen your case to be able to say "I understand the risks are x, y and z, but..." And if that doesn't work, go with the crying!
FWIW, if the baby does turn and you end up going for a vaginal delivery everyone I know who has had a bad first experience has found things much easier second time round - and one of them just produced an 11lb whopper. It may well be very different this time - your body knows what to do and you are likely to be less shocked by it all!
Good luck - I hope it works out for you either way.