Almost every job has an element of bullshit. And even if you aren't in a full on bullshit job often if you did disappear someone else would come along and take your place no problem.. So ultimately I wouldn't worry about that side. I'd more worry about your happiness. Does this get you down? Do you think it is unsustainable for you? Can you just decide work isn't your passion but you will do it to pay bills? Or do you need something more?
Be really sure about teaching before you switch. As you say, get a job as a TA. I have taught in a few types of schools and they all have one thing in common: the only way to get through the workload and intensity is if you truly enjoy what you're doing but can realise when it is time to say 'enough' or cut corners sensibly. There are many, many bullshit job elements to teaching. Amongst many lovely parts.
Initially you'll be overwhelmed, out of your depth and stressed overthinking lesson plans because a usually painfully picky assessor will come in and rip your lesson apart. Teaching is a full on, fast paced job. Your days fly by and no two days are the same. You are an educator, a performer, a counsellor, a mediator, a data cruncher, a writer, a social worker, a planner, an evaluator and a constant role model. It will grind you down and lift you up at the same time. You can never finish your to do list and the impact is either on a child's future, or your outcomes in some sort of management appraisal system. Many school leaders are under immense pressure and it all gets pushed down through the system. You are given targets, "94% of your children must achieve this grade", "all your X ethnic minority pupils must make 4 points progress at least".
It isn't about going in, chatting with the kids, teaching them to add, marking a few books, telling parents how their darling is doing so well and walking home again. There is SO much more to it and you need to see it and understand what you're getting into.
The holidays are there for a reason. It would be near-impossible to sustain the level of energy required all year around. That and they can't afford to pay teachers the salaries for the equivalent of a usual 4 weeks holiday style job. The salaries are decent, not ground breaking, and they do account for the time teachers get off.
I personally wouldn't swap it for any other job and adore it. If I won the lottery I would still do it. But that is also with memories of the days I drove to and from work in tears due to fear from a bullying headteacher, spending every weeknight and Sunday locked to my 'marking desk' at home and feeling never-ending guilt over children who you don't feel you do enough for. This stage has passed for me - I am hardened by the job and have found an amazing school where workload and staff wellbeing are top priority. But that school is a highly privileged one with parents paying fees. These kids would do incredibly whether I taught them or not. So... back to the bullshit job fear 
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