Dentistry

[650lb Sumo]

Doesn’t NHS have a poverty level range, I’d imagine 20k should qualify and provide free healthcare for your missus

Too busy to read through and post more now, but yes

(1) NHS dentistry is free to various categories of people, including those on low income and on some benefits
(2) However there are differences regarding nationality and legal status in the UK - some foreigners may have to pay (more).
(3) Otherwise NHS dental treatments have set prices dentists can charge, which are lower than the same people charge for the same work privately. They throttle the flow of NHS patients, so most people if you call up a dentist which does both NHS and private treatment, and say "Hello I need a filling as an NHS patient", they'll probably say "Sorry we aren't taking new NHS patients." Maybe they'll add your name to a five-year waiting list. However if you then say "Oh ok I will pay privately" you will probably get a swift appointment.
(4) It's scammy practice, like 'changing your gas supplier' and prices changing lol. As though someone is going to now connect you to a different gas holder via different pipes and send you different gas.

(5) With that being said if the situation really is an emergency the person should be seen quickly and should be able to claim on the NHS. Being it's an emergency, you can tell them you don't have the paperwork available now but put me down as NHS and I will retroactively claim. Then retroactively claim. Which would limit the cost to the aforementioned reasonable, capped prices.
(6) Remember the (2) caveat
(7) NHS won't cover like cosmetic vanity stuff, non-medically necessary stuff, but if you can't get emergency dental treatment on the NHS things are worse than I thought. You do hear about absurd waiting lists for urgent non-dental treatment and even multiple-hour waits for ambulances or at A&E though.
(8) If I were a low-income person needing urgent medical treatment and being quoted high prices in Minecraft, I'd look into just not paying - signing finance and only making the first payment etc. What are they going to do lol? Nothing bad. People have different tolerances to this kind of stress though, some couldn't stand it.