Hello!
Firstly, I wouldn't worried about being "laid back". There's a laid back teacher in my current placement who expects high standards from all his pupils and is amazing with behaviour management. I don't think this means you'll struggle.
There is a lot of pressure, that's true. It always feels like there's something to do, but I have a perfectly great social life. I'm good with time management and knowing when enough is enough. I don't do work at home, even if that means staying at school, and since I started in September, I've done weekend working about 4 times? Others will have vastly different experiences of this, but I'm seeing my friends every week, spending weekends out and about or seeing my parents - I'm really enjoying it. People manage to do this course with kids, so it's not all life consuming.
If you're not sure, if you're in England, have you looked at the School Experience Programme? I know you mentioned you did a TA placement, but we're you fully aware of what the classroom teachers were doing? Might be worth just doing a couple of days to double check it's what you expect. If you're in Wales (like me!), I emailed every secondary school in Cardiff and EVENTUALLY got one to let me come in for a few days 😂
Don't worry about missing deadlines for application - Maths is a shortage subject and you can pretty much guarantee theryll be spaces up til August. It's better you spend time being totally sure than rush in with an application.
I'm doing Physics (similar to Maths? Ish?) So feel free to ask me any questions if you have any more.