OP shoiuld not rely on settings to get what he wants and using the code is safer IMO. Going in the other direction for me I experienced what he is trying to avoid and get over it as described in this recent post:
https://aseannow.com/topic/1280019-keep-uk-sim-switched-on-or-not/#comment-17774666
I must look to see if there is a similar code for O2 UK to disable data as it would be more convenient than my method, but it was not brought up when I spoke to them about my issue.
I too have a Halifax Clarity and it's easy to avoid charges too, or keep them to a few pence. My concern with the HSBC product is the "rate of the day" is determined by them so may not be as good as the Mastercard rate you get when using the Clarity card.
Only a test will tell for sure.
It sets it's own exchange rate so even if it's better than the ones shown in the HfP article mentioned it would be good to know if it also beats Visa/Mastercard exchange rates. If not, a regular fees free card would probably would be a better option.
How old are you and do you have any pre-existing conditions?
For a comparison, my UK issued annual policy last year was less than £40 GBP. Worldwide cover except USA. Declared one pre-existing condition (no loading) and in my 50s.
Can you give an approximate amount for the different lenses to give an idea of what to expect? A local hospital in the UK offers:
Monofocal – corrects either short or long sight, with a choice of three focal points
Toric – a monofocal lens that helps correct astigmatism (a problem with focusing)
Multifocal – corrects both near and distance vision, like varifocal glasses
Are there any others available?
There is some link between them but I'm not sure of the details. The thread it was discussed in mentioned an initial check being done at Bangkok Pattaya (maybe they had the required equipment?) before the surgery at Jomtien.
I'm planning cataract surgery (one eye only) soon and recently noted this pricing in a thread in the Chiang Mai subforum.
Another option I've seen mentioned is Jomtien Hospital offering a special deal of ~40,000 baht.
It doesn't because Santander doesn't have such a policy. As above, they may close any accounts for a variety of reasons, including those of non-UK residents, but being non-resident won't be the reason.