I also can remember having sun-light treatment, it was towards the later years of my time in junior school, I think. I was sent for sun-light treatment after attending a school medical, I believe they thought I was not "developing" as well as I should.
I was excused from school one morning each week, my mum would pick me up and take me to Maas Road school clinic in Northfield. Once there we would enter a large room and I would have to undress to my underpants and wait my turn for treatment. The room would be full with other boys, all in the same state of undress as me, waiting with their parent for the same treatment. My mum would always start gossiping with the other mums while we waited. Most of the time there would only be enough chairs for the parents to sit so I and most of the other lads would have to stand while we waited. I know I seemed to wait for ages because my mother always wanted to get there early, to ensure we were not late. I think the mothers would treat this as an occasion to catch up with the gossip. We would then be called over for the treatment and have to put the goggles on and sit on a bench in front of the lamp for a period of time. I think there would be about ten at a time getting the "treatment". We would then have to turn round and have our backs exposed to the lamps. Afterwards you would get dressed again and return to school.
If I remember right this took place over a period of say twelve weeks, then there would be a break and then another period of treatment. Can't remember how long this went on for, maybe a couple of years. Much, much later I discovered that this treatment, far from doing you any good, was actually quite harmful and did cause skin cancer in some cases. It was a scandal that was covered up quite well by all concerned. Probably would not happen nowadays, but I still feel quite bad about how I was treated.