Teaching and Piercings Watch
For instance I recall a Maths teacher whose nose piercing had to have tape over it because students were not to be encouraged to have nose piercings in school (it may well have been against school rules at that point for students).
Realistically as long as yours looks neat, not extremely obvious and isn't the topic of a lesson plenary then I think you'd be safe. If you wanted a neck full of tattoos and stretched lobes then that's a very different story. Doubt many heads would pay much attention and the suggestion to not wear for interview is a wise one I think. If it looks and is treated subtly enough you should be fine.
I've been looking forward to getting a scaffolding/industrial piercing for ages now and finally have the chance to get it done, but I will be starting my secondary school teacher training course soon. Will this cause problems with placement and future employment?
It also depends on what you'll be teaching- obviously for PE, something like this would be a no go for health and safety reasons. If you're art/drama, they seem to get away with more!
You'll also get kids asking about it- personally I was fine with this and happy to chat to e.g. Y10 girls about whether my tragus piercing hurt and about whether it was safe/how to heal it. For something more obvious like an industrial piercing, I think you'd get more negative comments from some kids- which is just another hassle when you're trying to establish your authority with a class.
In terms of employment, it will be an issue for some schools, but would you want to work at those schools anyway? I kept my piercings in for interviews whilst otherwise looking professional- but I'm in a shortage subject and was pretty confident about finding a job!