From my own experience, temping can often lead to permanant jobs. It is also a great way to get a broad range of experience in different job environments. Not to mention it looks good to potential employers that you are temping whilst looking for a permanant role.
I did a degree, but unfortunately have never used it in any jobs I've had. Experience seems to win over qualifications, but having both is definitely a bonus imho.
Having said that, I couldn't have survived without the support of my mum, when my first relationship broke down and I was left a single parent, she let me and DD live at her house rent free until I got on my feet again. (Although I did contribute to household chores and food shopping as much as I could) This is when I went from temping to a permanant job and was able to get my own place and move out.
My DD's dad was older than me and good-for-nothing, divorced with 2 kids he didn't support, no proper job. He left me for a teenager half his age(who is expecting his 4th child). I know the OP said her DDs BF is hard working, but just using this as an example of being in an unsuitable relationship ... I couldn't see it at the time, although looking back I'm so glad myself and my DD are away from him. I don't think you can ever tell anyone they're in an unsuitable relationship, they must figure it out for themselves.
I'm now happily married, full time job (although not ideal, it brings the money in), own home etc etc! I think OPs DD just needs to see that earning money takes priority over finding the ideal job unfortunatley, a lesson that won't hit home unless her existing financial crutch is taken away.
(As an aside, I'm 29 and my DH is 31 and we still like to go clubbing, I'll be very sad if I ever 'grow out of it' as mentioned somewhere on this thread!)