In 2004 I was taken in to hospital in Stockholm with acute abdominal pains. Before admission I had to pay about £6 and then got to lie on a trolley in a corridor for 4 hours until a nurse finally gave me some painkillers. These were so strong that I felt great, discharged myself and went to dinner with some friends. They drugs wore off at about 2am despite half a bottle of red so I was back in hospital at 3am, paid another £6, and finally got to see a doctor at about 6am. Gall stones, big ones.
The surgeon thought he'd be able to operate in a couple of weeks so I asked if I was fit to fly. He said OK so I got on the next BA flight home having been stuffed full of happy pills. I got a taxi from Heathrow straight to the local A+E where I waved my Swedish case notes and scan. These were very helpful as the NHS ultrasound machine wasn't working and the words were similar enough for them to guess, apparently.
In retrospect one of the stupidest things I've ever done. The painkillers were strong enough for me to have flown without the plane and I didn't tell BA I was sick. That could have ended badly. But I was damn glad to be in the hands of the NHS despite its failings.