Is this likely to be asbestos in the ceiling above my bathroom?
It is hard to tell from the photo, but it looks like long, man-made fibers which is not a common form of asbestos in residential homes.  The common form is vermiculite.  I have a home built in 1965 (in the US) and it had "rock wool" batting which I was concerned about, so I did a fair amount of research.  This article helped me feel better.  The only way to know for sure is to send a sample to get visually inspected at a lab.  I had some plaster checked and it was not expensive.