Does anyone have any advice about it?

I've been looking for a way out of my job, and engineering as a whole, for a while now. I've applied for a few office jobs and got nothing. I got an interview for a science communication job and completely fluffed it.

Today on a job site I saw an ad for a tutoring agency, specifically for maths tutors. As an engineering graduate, I met their criteria to teach maths up to A-level (end of high school). I loved high school maths and I've loved the engineering outreach work I've done with kids and teenagers.

As I'd be self-employed in effect, I could part time it for a while and scope it out, without quitting my current job. But part of the problem is that my current job is ridiculously long hours, so I'd be knackered. Ideally I'm looking at this at my main source of income, at least for a while. It pays well per hour, but of course is less secure than my current salaried job. I have no ambition to get staggeringly wealthy; I just need to pay my bills and have a little money over for theatre tickets.

Does anyone have any advice? Also, agencies: I've checked it out and it seems legit, but is there anything I should be wary of? I don't want to get scammed!