Surely you had to notify nursery if your child was ill? And pay attention to term dates if it was term time only?
I agree that being in school does change the ‘rhythm’ of your life as it’s ruled by term times and school events, but that is the case for all schools, in varying degrees. Keeping track of school terms and holidays - that’s what a calendar is for! Homework in Reception tends to be limited to reading and maybe some phonics work, so you don’t need to be sitting down for an hour every evening. School events and dressing up days seem to happen a lot - I would note them in my calendar and set up a phone reminder as soon as we got the email, or multiple reminders if I needed to order a costume, bring in supplies etc. The events seem less onerous because your child is looking forward to them, so while it might sound like a lot now, it will settle down. If there’s a class WhatsApp group, make sure you join it, as it’s great to be able to double check dates if you can’t remember when X event is.
I assume you are a SAHM as you don’t mention anything about work, but do mention a younger child. That will make it easier as you don’t need to be sorting out wraparound care and holiday cover, which was our main stress when DD started school.
On a practical note, think about things like getting enough school uniform to cover a week, making sure your child can recognise their name and do things like going to the toilet themselves, that kind of thing. If they’ve been at nursery I’m sure it will have helped get them used to a school environment, lining up that kind of thing.
As the school is in a nearby village, how is the drive to school and what is the parking situation. Do you need to get there early to get a parking space? Are the local residents unhappy about school traffic so you need to be extra considerate?
I found the social side harder as I’m naturally quiet and feel socially awkward, but I think you really have to make that effort. I tried to present the best version of myself in those first weeks, which sounds awful, but I just tried to keep the chat lighthearted and sound like a ‘normal’ person rather than revealing geeky hobbies straight off, for example. I eventually became quite friendly with a few of the other mums, but was happy to chat with the other parents as it was a small class and we all got to know each other. Small talk in those first few weeks tended to be about how your child was settling in, had they been to nursery before, are you close to the school or do you have a longer journey here , fairly generic stuff.
In the early years, play dates usually required the parent to stay as well (which I was happy with as I didn’t want to leave DD with a total stranger), but this meant that play dates tended to depend on parental contact in the playground - knowing that A was B’s mum so you could approach them. There was a park near the school so we often went there after school and I’d get chatting to the other mums. Luckily a couple of them were outgoing and friendly so it was easy to chat them, then chat to their friends, and so on. It does depend on the demographic of the school - do a lot of the parents work, so use wraparound care and aren’t there at pickup to chat to.
Good luck! It will seem daunting, but after a few weeks you’ll get into your new routine.