Following further investigation revealed that, as you can see from the first screenshot, the scene was not in the scenes folder. Inside was the default scene. I moved the correct scene into the folder and deleted the default. That fixed the text issue.
The image was caused by the way that I added it to the canvas. I dragged and dropped it directly into the scene, and (not sure how wrong that was?) caused problems. I deleted the image, and added it again with rightclick > ui > image. I then linked the image from the assets as normal, and fitted it to the canvas as normal.
Seemed to have fixed that issue too. So huzzah… problem solved. I hope it helps someone else in the future.
Happy coding!
Ed