Personally, I wouldn't waste my time with university with your qualifications. Unless you're going to get into one of the top Russel Group universities, an economics degree isn't going to do you much good. If you end up at a crappy university, you are paying a vast amount of money for a worthless qualification, and you'll be no closer to a job at the end of it.
Have you considered joining one of the other services, police/fire brigade? Good career, solid pay, lots of specialisms open to you, cushy pension after 21 years.
It's not a popular thing to say in today's 'shoot for the stars', 'everyone's a winner' society, and it probably won't be popular here as many advocate packing up and just 'doing you' in some so-called 'pussy paradise', but in my view one of the best things someone like you can do in your situation is break the cycle of low opportunity for the next generation - your children.
I've mentioned on here before that, unlike you, I come from about the best, most privileged background anyone could possibly hope for. But it is only because 4 generations of my family have made tremendous sacrifices to ensure the next generation started life a little bit further on than the last. My great, great grandfather was a blacksmith in one of the naval dockyards. It is hard to overstate how far my family has come in terms of expectation and opportunity over those generations. The opportunities I have are the result of previous generations making conscious sacrifices they would never see the fruits of.
It's unglamorous, and in some respects thankless, but such sacrifice and foresight was once more common, and made us a very great people indeed. A steady, if unspectacular life, is not without tremendous value, meaning, and deep satisfaction. Such a life, and a commitment to a particular philosophy, would provide your children with opportunities that circumstances have most likely denied to you. If that were the worst case for all of us, we would be a very great people once again, within just a few generations.