I hear you. I've been living on a Greek island for the last 5 years where "tech job" has little meaning. Aside from working in bars and yachts I've been working mostly freelance getting whatever clients I can get on my own, making websites/web apps or doing some digital marketing.
I've been back in Scotland for almost 4 months now and after countless interviews I still haven't landed a job, and of course I can't afford one of those ludicrously expensive bootcamps. I've been working through freeCodeCamp.org which focuses on web development with javascript (front end and back end), and as the name suggests it's free. It's supposed to be quite reputable and has tests and certificates they offer which you can then put on your CV/resume.
Maybe there's an equivalent for .NET or Java.
I would also suggest adding to your portfolio with your own projects, even if they're just proofs of concept. Word of warning though, from my recent experience everybody wants knowledge of frameworks. I've rarely been asked about algorithms, data structures, design principles, or anything that makes a good programmer good. They all want framework knowledge presumably because frameworks protect programmers from making common mistakes. This is quite annoying because my CV includes a decent list of published apps, a working programming language which I used to make a lot of apps, usage of cool APIs like Stripe, knowledge of lots of programming languages, you name it. But nope, as impressed as they are, I need to know more about React or Laravel or whatever the hot new thing is.
So I would say find out what the swankiest frameworks are for Java/.NET and use them to create and publish a simple application and stick it in your resume, and if you can, find an equivalent to freeCodeCamp.org. If that doesn't work then good luck collecting $15k and having 14 weeks free! Ha!
\"everyone forgets a semi-colon sometimes.\" - Phaelax