Just to add a slightly successful story for you: I got an elective section booked (in 9 days!), on "maternal request." I got it because of psychological distress - my previous labour was vaginal, no tears, no intervention, but DS ended up in SCBU and I didn't know for 12 hours if he would live
I'd say your GP is defo your first stop. If they know you and you tell them what you want and why, they should support you through the whole pg, starting by helping you to find a sympathetic consultant. Be prepared for a long process. It can be mental torture to have to explain, repeatedly, throughout the pg, to different people (MWs, registrars, and consultant) why you want a section. Ultimately you will need your consultant to agree, nobody else really matters, but you have to endure the process till you get a meeting with them and they put it on their books. I was misled early on, thinking I'd have my section, when in fact I learned at 34 weeks upon meeting the consultant (finally) face-to-face that I'd not been officially "approved" yet. Don't stop till your consulant tells you it's approved.
You should also prepare to hear a lot of negatives about CS from everyone in the NHS. Each person I spoke to in the system told me something different and negative about the risks, and nobody explained the benefits to me. Some of the things I was told were plainly wrong (e.g. my risk of infection was higher because I'd previously delivered naturally. Utter crap).
Besides endurance, you'll need as much research as possible so that you have a complete, balanced & realistic view of all your options. Everyone else will probably have an agenda, not the whole story. That way you can make up your mind and stick to whatever you decide is best, for you. Good luck!
(my NCT teacher had a good, short, balanced book on CS - worth checking your local group for resources if you don't have anywhere else to start)