"Grim and bear it" I really like that.
Housecalls seem to be a bygone thing here in the US, I don't know how it is in the UK.
I think your best-bet would be to make an appointment with a dentist and just tell them you have a dental
phobia. This way the receptionist and doctor will be at their most accommodating, since it's problem they've seen a thousand times before. Any "weirdness" on your end will just be chalked-up to that. Personally, it's what I would do. You get compassion without the evisceration of telling a complete stranger about your SP.
I hope this helps. I know you say it's impossible to actually go, but I would've felt bad if I hadn't offered a possible solution.
Same goes for opticians.