4 years ago I had my partner take photos of moles that had changed colour on my back. I used the MySkinDoctor app https://www.myskindoctor.co.uk/ to send them to my consultant dermatologist (who, at the time, I had never met -- having just moved to a new area). Upon review they arranged for an in-person appointment and I was seen within a week or so. All through the NHS.

So yes, taking the photo at home is perfectly doable. I still went to hospital though.