At this particular time, yes that works. Do you really think though that they will continue to allow the exact same extension for retirement on an 'O' with no insurance as you get on an O-A needing Insurance? They very obviously want those over 50 years old to be on this Health Insurance scheme.
The majority of immigration offices won't allow an extension for being married against an O-A visa. An O-A is specifically for being over 50 years old and retirement.
'If' they allow the switch to extension for marriage, you'll still be running from the original O-A. How that is going to work regarding medical insurance, only immigration can say.
I am wondering how your getting to the end of the application without choosing the correct visa and uploading each page to be able to see this biography thing?
has said. I'll have a £5 bet you selected the wrong long stay option at the very beginning and it's now defaulting back. Perhaps you can be so kind as to let us know if the E visa application website has been updated to include the mandatory Health Insurance for O-A Visa applications.
They are not interested in looking through reams of paper in a foreign language when entering at immigration. Most people cannot understand an insurance policy themselves. Hence they want a certificate.