Apparently Are You There, God? It's Me, Margaret is being made into a film.
My mother had many faults, but she was pretty good with periods. We saw Tampax around regularly and sometimes a bucket of cold water under the bathroom sink, with knickers soaking. We had the Tampax lady at school when we were about 10 or 11, and we all got a free sample box of the mini Tampax.
I started on a Sunday afternoon in the summer holidays between middle and secondary school, which was pretty good timing - the most traumatic part was having to wake my mother from an afternoon nap to tell her. She put me in the bathroom with a selection of pads and tampons, and told me to see what suited me, to call her if I needed help, and reminded me I swam quite a few times a week. I used Tampax from the start. It was mid-'80s and I never really looked at pads, but I'm pretty sure my mother had gone modern and I was only offered stick-on pads. I only knew of looped/belted pads from reading Judy Blume.
I don’t think there was still an incinerator at school - we certainly had cubicle bins - but one of the 6th form colleges I later had evening classes in had a n incinerator in about a decade ago, and I knew what it was, and that it could be referred to as a "bunny" so I must have come across them before. It wasn't functional, though, and that block of the college was refurbished about a year later, and it was removed entirely. I wonder if Bunny was a manufacturer name or something?
We did have PE knickers at secondary school (bottle green), with normal knickers underneath. For outdoor sports, a PE skirt was worn as well - it had a little plastic toothed track (bit like on a cable tie) that a little metal fastener slid along then locked into place. For gymnastics in the hall, no skirt. But it was all girls at secondary, so we didn't care. I have no memory of the showers at secondary, but we certainly had communal showers with very bright lighting and white ceramic tiling at middle school.