Bless you. I'm calling my doctor tomorrow.
Normal preface of I am not a doctor, please consult your own medical professional. Rang my doctor this morning. I expected a normal response of "Oh! the internet!" from him, but in fact he was up to speed about the information coming out of Italy, and agreed to change my medication from an ACE inhibitor to amlodipine from today. Official advice is still not to change people's medication. That may be revise once the system has had a chance to look at the information from our own population.
He said that the choice between medication for high blood pressure was a balance of things. ACE inhibitors protect the kidneys, and for people who are at risk of kidney disease are the far better choice, also for those with history of heart disease or stroke. It's a balance, and apparently Amlodipine has a variety of not very comfortable side effects which are usually transient, and does not provide kidney protection. His view was that I should switch but the dangers for my ex were in the other direction and he should not. So it's a case by case thing.
The point is that if you know you are on the drug and it increases your risk of catching the virus and of getting the serious symptoms like pneumonia, you have to behave as though you are in the shielded group, don't go out of the front door, and don't take ANY risks with deliveries or visitors at all.