I second going to shadow in a school for a while OP, I don't think you really know what it is you think you want.
If you have a KS3 class of 30 in front of you, they will likely not be set. Some of them will not really be able to read or write so they can't get on with an independent task, some will have attention difficulties and not be able to listen to you or work on a task for more than 3 or 4 minutes before they start messing about, some will have social communication difficulties and anxiety and frequently become emotionally disregulated which may mean they cry/ shout/ swear, some will have SEMH which mean that they will wilfully test your authority and intimidate other pupils. Some will have demand avoidant profiles that mean they will oppose whatever it is you ask them to do.
Then some will be really bright, and desperate to learn. Those ones may really resent you if you can't engage the others in the class. They and their parents might lodge formal complaints.
Then there will be some quiet 'middle' kids whose education you can see slipping away.
When you get that class through an hour of learning... the next one sit down- and they are actually a difficult class.
Repeat that 5 times a day every day for weeks on end and you will, I think, understand a new depth of emotional exhaustion.
And, dealing with that stuff is the GOOD bit of the job. Don't get me started on the stooped hoop jumping we have to do out of the classroom.
If you can sit down with a class like the one above, and genuinely love to be with them. Enjoy the adrenaline rushes when they throw chairs across the classroom and the oxytocin overload when they actually learn something, and have the resilience to do it over and over again even after you've carried a baby around between 2 and 4am, you will be ok.
If not, advance straight to M&S.