Would I be in debt with universal credit?

UC is generally paid in arrears so assuming you told them when you expected to work/get paid you shouldn't end up in debt to them. They're a lot better about stuff like that than they used to be.

When I was zero hours I had to notify them every week/2 weeks of what my earnings had been and they took it into account as my boss didn't do the auto PAYE thing.

How do I notify them of my hours it doesn't ask me to when I log in?

It's been a bit since I used it but I'd either pop in in person every 2 weeks with my payslip (likely not an option just now) or I'd add the details as a basic journal entry on the UC system. There wasn't a specific 'hours' screen I filled in.

At a basic level your obligation is to inform them of the work you did and what you were paid, that's about it. Figuring out what you owe/get ect is supposed to be their problem.

Oh okay so I just add a note for my work coach of the hours I've worked or does my work notify them of the hours I've worked? I don't get paid till 2 weeks after my uc payment so I still need the money. My work coach hadn't explained what I need to do properly.