I am having an ELCS for my first baby due to mental health reasons (anxiety related which are quite complicated, but revolve around a mistrust of doctors). I sought out help before I got pregnant and found a hospital which had staff who had an interest in the area and had experience in dealing with similar cases.
As a result unlike you, I have had an extremely supportive team and this has made the world of difference to me. One of my fears was exactly people trying to persuade me to change my mind and not taking me seriously. They have all seen me hysterical and have realised that I need them to listen to me and respect how I feel. The general approach at my hospital for women in similar situations is to work on building trust with them and support them in whatever decision they ultimately make, which sadly seems to be completely the opposite to what has happened with you.
Its my understanding that there are very few places in the UK which are like this unfortunately, as understanding of the subject is extremely limited. There are a lot of HCPs who really do not know how to handle the situation, and have their own ideas about what is 'best' for women who request and ELCS. Much of it is tied to ideological beliefs that a VB is always best and a CS is a 'bad' thing (which is backed up by political and financial concerns). They are often under pressure to reduce CS rates.
The reality is this: NICE realised that there was a problem, and changed their guidelines to reflect the latest evidence about women who request an ELCS. Previously mental health was an overlooked area with many HCPs failing to recognise it as a valid reason to have an ELCS leading to a massive disparity of care across the country. The guidelines were supposed to stop this - but this has had mixed results in improving the situation. The guidelines have been controversial, but have been slowly changing these attitudes and breaking through ignorance on the subject, though sadly not universally or quickly enough.
The guidelines compared planned VBs (which include assisted VB and EMCS which are a result of attempting a VB) and a planned CS. Their conclusion was there was very little difference between the two in terms of risk for the mother and there was only a slight difference for babies (slight increased risk of being admitted to SCBU for ELCS babies). But they felt that on balance, when you took into account the potential risks to mental health from denying access to an ELCS, that women who wanted one, should be allowed one. The conclusions of the guidelines are however flawed in so much as they only look at first time mothers, and don't consider the knock on effects for subsequent births.
So if you consider this as the 'official line', unless you have other medical complications or are considering more children (which from your story sounds like it is unlikely) what the registrars are doing in trying to scare you, is both factually incorrect and damaging to your trust in them. They are just wrong in both their words and deeds.
My consultant has been brilliant in stressing that my request for an ELCS is based on medical NEED just as much as any physical need for an CS rather than just being a choice which has massively helped my confidence on the subject. Attitudes that don't see mental health reasons / maternal requests based on mental health as being 'as valid' are common and the whole area is still steeped in dated stigma and ignorance. In fact the evidence shows that women who choose are more likely to need support than the average woman. Constantly have to defend or justify their position is actually the last thing they need. Put it this way too: you would not get many registrars challenging a consultants decision about an ELCS for physical reasons... It says a lot about their own beliefs and lack of knowledge that they think it is ok to do so under these circumstances.
Please, try and focus on the fact that your consultant HAS been supportive and DOES seem to understand where you are coming from. There ARE people out there that do 'get it'.
I don't have any other advice or gems of wisdom with which I can try and reassure you with, other than to say, that if you feel this is right for you, then it probably is. You seem to lack confidence in trying for a VB so if you did and things went wrong, you'd struggle to cope. With an ELCS you are at least mentally prepared for it at this stage. Those who have studied the area, support how you feel and do not think it is unsafe based on the research available especially when taking into consideration your mental health.
I am booked in for a few weeks time, so I can't give you my views/experience about the end result unfortunately. I can only wish you good luck and hope that the experience is kind to you and heals a few wounds.