Thanks for yours and everybody else's concerns, advice and wishes. So, we have some answers now - a bit of a curved ball is incoming.
I had the CT scan today, which showed no blood clots in my lungs, even though the blood test showed an indicator (D-dimer) that was more than ten times over the normal level, so somebody still needs to figure that out.
I was very lucky that the lung scan went just a bit lower because it showed that my gall bladder is like a bag of marbles, even though I have no significant symptoms of gall stones.
At least I can ride my bike again without worrying. I'll take it easy for a bit, and hopefully my heartbeat will come down as I get fitter.
The service I had from the NHS has been very good. They're quite disorganised, but fairly thorough (so far) and cautious. They didn't even put DNR notices on my trolly, nor try and inject me with Midazilam and Morphine. It was very sad to see all the other patients there, most of whom were substantially worse than me, and though they put on a brave face, I could see that they were worried about what comes next.
Now we can all relax and get back to normality. I don't think the treatment for gall stones is too bad these days, but, looking at the size and quantity of mine, it wouldn't surprise me if they decide to whip out my gall bladder, like they did to my sister, or do some other surgical procedure. It's just a pain that these things always happen in the summer.