I'm a secondary English teacher- or at least I was until August. I've left now to be a SAHM although i still do some cover when I need the money.
To be a teacher you HAVE to have a degree and English and Maths GCSE (O level).
The PGCE year is extremely hard work as is the first year of teaching. Once you get into your second year you have some resources so it gets a bit easier.
The hours are long- speaking as a secondary teacher I would spend at elast an hour every day marking and preparing. All of Sunday was spent marking and prepping. Most half terms were spent marking exam papers or coursework. Christmas and Easter were spent marking and preparing. Obviously not the whole holiday but at least half of it. The summer hols were my hols- I didn't do anything until the 6th week when i used to start planning etc for the coming term.
As a teacher you have total responsibility for the lives and education of up to 30 children in your class at any one time. PLus from the second you get into school you are on 'duty' so to speak- you are a responsible adult and 'in loco parentis'. Walking the corridors to the staff room at break if you see something that requires attention then you can't ignore it (fight, bullying, fall etc etc).
There are disclipline issues in a lot of schools, a lot of paperwork, integration of SEN pupils and all the paperwork involved. Report writing, parents evenings.
As a teacher if you suspect abuse you have a professional responsibilty to act on it and can be held accountable in a court of law if you have ignored something.
As a teaching assistant you arrive at school at 9 and leave at 3.30. You are given a timetable and take guidance from the teacher. You cannot be held accountable for classes as you should not be left unsupervised. You have no reports, parents evening, marking etc etc etc. The downside is the salary I spose. The TA's at my old school were probably on about 13k pa whereas teachers start on about 19k.
My explanation of TA's is from what I saw in my school btw- if anyone reading this is a TA and you do more than this then I apologise