Thank you, you're absolutely right. I have the Watch 3 and I have been waiting for the upgrade to enable the ecg and BP abilities. I believed this was to be completed on 22.02.21. there was in fact an upgrade, but not to achieve that.
Are you using a Samsung phone? These main features your looking for will only work on a Samsung phone I believe. If you are using a Samsung and have updated your watch software. Then you need to download the Samsung health monitor app from the galaxy store. Follow the instructions on how to do a ECG or blood pressure.
I'm also in the UK. And my active 2 has the ECG and BP. It was made available with the latest update. Have you looked in the galaxy Wear app and see if you have the ECG and BP widget to add to the watch?
I also had trouble downloaded the Samsung health monitor app as it was not showing up in the galaxy store. The way I had to do it was once I added the ECG and BP widget to your watch. This is in the galaxy Wear app under widgets. Once I added the widgets I opened it on the watch, you will then go to learn more and then it will have download app. You may have to scroll down on the watch to see it. Once I clicked download it then showed up on my phone to download the health monitor app.