It will also depend on the type of landlord.
When I was 18 (10 years ago) I moved around 2 hours away from home to Bournemouth. I got my own 1 bed flat for £650 per month and at the time I was a HCA earning, iirc, £18k plus unsocial hours. Don't get me wrong, I had very very little at the end of each month but I made it work. I also changed jobs when I moved there but as I stayed with the NHS, it was a straight move. I just provided the letting agents with my signed contract of employment for the new role.
However, the things to note there are that renting was miles easier and cheaper (though your DD is on more than I was), I rented in a place where there was an abundance of properties, I had a fixed contract (0 hours is tricky - though some will take 6 months payslip and a guaruntor) and honestly I'm fairly sure working in the NHS gave me some credit. Also, I rented from a landlord who had 80+ properties. They weren't a couple renting out their other home and totally reliant on that money. Which I guess made them more lax with regards to who they rented to.
It wasn't easy by any means and I definitely had a learning curve and a half. But I had a really supportive family and the odd £20 tesco voucher in the post really helped me out.
In todays market, she'll likely find it quite difficult to find somewhere, but not necessarily impossible depending on the area.
I'd suggest possibly looking on OpenRent as I found the lack of estate agent helpful at the beginning (though did end up renting off rightmove).
Best she can do is enquire. If she finds somewhere then she'll likely make it work and eat a lot of beans on toast. It's all experience! If she can't find somewhere then it may help her lower her sights to a house share. I imagine she'll find it easier to adjust to that idea off her own back rather than being told she can't do it.
I wish you luck!!