How do you deal with the trust issues posed by that questionnaire? I have suicidal thoughts most days, but I'm concerned that revealing this to an NHS doctor would quickly result in my freedom of choice on what happens next being taken from me. Seems like one of the few cases where US healthcare (where you are explicitly a customer as well as a patient) has some advantages.
Really though, seek help. It is unlikely you'd lose choices (eg be sectioned) if you're asking for help and engaging with that help.
I pick at this stuff in my own head all the time, and just don't have enough confidence in doctors to believe they could tell me anything new. Being able to skip straight to pharmaceutical or other non-talking solutions via a disclaimer would probably mean a lot more people like me would seek help.
Antidepressants are strong stuff. Some years ago I hit a bit of a snag and went to a doctor and got just this, a prescription after five minutes of talking with helpful advice like "get a girlfriend" or "study something else". Stuff really worked... except in the wrong direction. Not an exception either, common enough they put "suicide" as a side effect in the fine print. I think if you're gonna take something like that you need some kind of feedback/monitoring and test different drugs until you might find something that works right. A hands off fire and forget prescription like I got likely won't work for most people.
GPs have been enormously helpful to me with this stuff. Most are very understanding. If you can do an online appointment booking that might help too - so the immediacy isn't an issue so you can write the appointment reason very clearly and revise it as much as you want before hitting the button. Otherwise, tell the receptionist you'd like a phone appointment (for the distance that gives psychologically) and that it is for a mental health issue. The diagnostic criteria for depression are fairly easy to satisfy - it is mostly about low mood for 4+ weeks. Keep details to a minimum you need to get a prescription but be cooperative if they probe.
Whatever you do though, don't just suffer. Tell your spouse how you feel too. Get some help.
I have kinda the same problem. I've had depression for a very long time - stable, but consistently declining. I get the "... or I could just kill myself" xapata mentioned a couple times per week and the reasons I don't are basically "that sounds like work" and "that would make my mother sad". Which aren't exactly good reasons, I know, but so far I've done very little actual self-harm and I very much don't want to get involuntarily admitted. I really would like to get help to deal with depression. I've battled it out alone with it for 15+ years and I'm not exactly winning that fight. But- anyone that's qualified to offer that help is pretty much legally required to admit me if I answer their screening questions somewhat truthfully.
Damned if you do, damned if you don't.