To those relying on data protection, you need to contact each institution or company personally and get a specific reminder or note put on your file.
I'm afraid I've experienced how easily people break data confidentiality when someone asks in the right way. You cannot rely on someone's ability to do their job just generally when it comes to important things like this. I'm sorry I don't want to scare anyone, but I didn't want to read and not comment.
Shockingly, in the last 3-4 years I've had a gp, the same gps receptionist, the council, transport for london, a physio practise, social services, a care agency and three hospitals all break confidentiality wrongly and without a second thought. It's all to do with the way someone asks.
Most of that was one person by the way as you've probably guessed (!), but two weren't, which are the ones I was most horrified by as I could explain away the others by blaming the other party.
The one who did most of it was an employee / former employee who had err, boundary issues (ok I want to say was a nut fuck bitch :) ). I'm disabled and employed her as a home PA. She over reached her position from the start but it took a couple of months for me to realise how awful it was and to fire her (with support of Mumsnet, ahh I'd forgotten that until I started writing this, people were lovely and made me realise that I was cowering from her and how it needed to STOP). Afterwards I found out she phoned up multiple health appointments and changed the contact details to hers... And they didn't even question it, and then I didn't get any calls as they phoned her mobile, and as she then picked up the phone and pretended to be knowledgeable it didn't raise any eyebrows. The bitch even registered her own car on my blue badge and got tfl to give her a discount on congestion charge as her car was registered disabled [shocked] found out that gem a few weeks ago when tfl sent a copy of the renewal to my home address. Bitch just have been using it this past couple of years and I never knew.
Someone phones up and says authoritatively they work for a disabled person and they'll be dealing with X today as disabled person is too poorly... And even health professionals who really should know better just blab out all sorts of personal details happily. I think it helps that she's a middle aged woman, who sounds very competent but not too posh on the phone. I also think people get awkward and embarrassed as soon as disability is mentioned, and are worried about being seen as not being kind to disabled person... Oh and for some, because disabled people are assumed to have less rights than a 'proper' person (grrr).
It wasn't even that having managed to get into one element of my life she used it to access the others. She didn't (I've checked quite thoroughly!) she just confidently and authoritively bull dozed over any flicker of a doubt.
One of the other times happened recently and was a one off but shows it wasn't just one scary freak that had a gift for extracting info out of people.
This was an 'official' who phoned another official though not colleagues or working for the same place, there was an assumption of professional courtesy and an assumption that id signed a data protection waiver - which I hadn't. I complained and the person who'd broken data protection was very upset and definitely felt guilty and somewhat 'conned', though the other person maintained they'd never said directly they had permission. And actually even if they had said I'd given permission, that shouldn't count for anything, as surely anyone can claim anything over the phone!
People believe what others say and it's easier to just go along with it than be awkward or sound officious.
And finally, the last one and the one that caused the most problems was when someone from adult social services couldn't get hold of me on my home phone so instead of calling my mobile, or emailing me or contacting the numerous other ways I'd given, they decided to call my parents instead who's details id given in the 'next of kin' bit but had emphasised verbally and in writing on the form that my parents were not to be contacted unless it really was a danger of death type situation. They didn't know I was serioisly ill, and I hadn't told them I needed carers to help me. Oh and I was not in contact with them and they lived 250 miles away... And I'd given two other contacts who lived close to me and could have told the idiot calling to try me on my mobile as I couldn't get to the landline quick enough, being physically disabled and all (idiot! grrr!). So that was how my parents found out I had a very serious illness, my husband had left me and our baby, and need carers.
And typically all my parents reaction was to get angry I'd given their details out to officials, and how I'd embarrassed them and put them in an awkward position! I took them off the next of kin details and if I did die I hope someone would let my mother know somehow at some point.