Do you think I have ruined my chances at a career

[hopelesslyunemployable]

When I got my first job out of university after a couple of months I accidentally (but without sorrow) reported them to HMRC. I’m pretty sure they suspect it was me. I left because they promised to put me on the payroll after a trial and then never did, I contacted HMRC to see what I should do about my tax, when I asked them if I should phone HMRC to ask about it they’d said “No! Don’t contact them!!” Which made me think the setup was super dodgy and I was uncomfortable there so I quit.

I never bothered applying for more jobs, felt paranoid that this company would talk to all the local employers and tell them I was a narc and not to hire me. Maybe that’s just paranoia or maybe they would do that, but hopefully even if they would they can’t know or be on good terms with everyone right?

It’s been 5 years since then and I’ve not had a job since (and I can hardly use that company as a reference). Did I ruin my chances for life?

My nephew dropped out of university and had a catastrophic collapse in confidence. Eventually the Job Centre got him into an employability scheme that led to a placement in an insurance company. They offered him a job at the end.
So it might be worth seeing if there is a similar scheme near you. Children's Centres might have links to similar schemes for mothers.
He's now living independently and happily.

Have a look at some cloud computing training. I know AWS have a programme called aws educate, you train online and gain access to the educate job boards with both AWS and partners. Loads of opportunities for women in your field at the moment!

I've been out of work for 12 years and before that I had a job as a waitress and a stint working in my local cinema. I was a sahm during those 12 years and also a student for a few years doing my degree. I now have a job in the public sector as a trainee that has really good career prospects. If you to in with a certain degree of confidence and apply for the right kind of roles I really don't think having 5 years out of work will be a problem. Forget about the hmrc issue, sounds like the company needed reporting, but it's not something you need to think about now.
Good luck op. I too decided I needed something tangible after being at home so long with the kids. I hope you find something you like soon.

Apply for jobs with the hmrc! Putting that you identified fraud that this resulted in a positive outcome from the hmrc and tax payers perspective is bound to be seen as a positive.