DM had me reasonably prepared for periods starting. On the day it started (in a PE lesson no less
I ended up layering up with toilet roll until I could work out a sensible time to get my supplies and use them.
Even so I was not "allowed" tampons for y9 camp and I was concerned that with water based activies, if my period turned up that month while on camp, that I wasn't going to be able to join in. I had been given spending money and snuck off to buy tampons for camp with it. Access to appropriate protection, free of embarasment is so important, especially at a difficult time of life when they may be hard to adjust to for so many reasons.
My cycles were highly erratic until after having children. Even as a teacher I have been caught out (and walked the corridors with a packet stashed up my sleeve. Similarly, many of my personal pads have been given out over the years, I suspect to girls who had been caught out rather than a deeper supply issue. They probably could have been supplied through the school office, but it is less embarasing to approach a trusted teacher.
As much as I love reusable products, and offering them as an option is no bad thing, particularly moon cups, they are not suitable for all circumstances and those without good access to laundry.
We need to talk about "period poverty". We talk about food banks, fuel poverty, costs of school uniform, but 50% of the population who are over-represented in politics, senior management and policy making will never have a period in their lives. Even on a mumsnet discussion about periods, it will always be very telling that the range of personal experiences with periods is diverse, and often women have little idea what periods are like for other women.