If you have a particular course in mind, well DO IT Do IT DOOO IT!!!
Not only will it make you believe in yourself, prove to yourself that you can think beyond lego and give you a qualification (and £15k+ of actually the best debt you'll ever have) you will also have access to your university's careers service.
My Uni's career's service enabled me, 12 years after I graduated, to access their career tools and funded projects and I now have a job I love (within the Uni as it happens) that are currently considering funding my MA. And I am someone who has relatively no idea what subject I want to study most, I just love study and I'm good at my job... surprisingly to even me, considering it's in a completely unrelated field to the one I'm in.
I went from an 8years+ SAHM graduate to an employed and employable member of staff within an establishment that really invests in it's employess and pays well enough, and I am not confined to just Uni Jobs forever, I've already been offered two jobs elsewhere for better money, but right now I'm happy where I am.
I now deal with many mature students (from 25 to 85) who study for different reasons and without exception get something incredibly positive from the experience. Yes, I am still in debt, I've barely paid off 1% of my initial loan, but there's no demands for payment, it comes out of my wage, and the amount is very small... what it's given me isn't just a qualification, but a feeling of self worth amongst the University Establishment, where they nurture you, guide you and support you LONG after you graduate.
One of my Masters Modules was free. I didn't continue with the full Masters because it wasn't 'me' or in the direction I wanted to go, BUT I can still refer to it in CV's etc., I receive ongoing support (that is entirely seperate from my employed role) and I feel worthy in a professional sense. In actual fact my 8 year 'break' has become something that is seen as positively (as I'm already proving my professional qualities everyday) rather than an obstacle.
It may not be right for everyone. I am not saying it's the best thing ever, but it's been the best thing ever for me and my head.
Mostly though, if the need to study at a higher level will not leave you, then you should do it, just because. If you can. Do NOT worry about the student debt. It's actually benefitted me as I had NO credit rating before it, I haven't defaulted on any payments and suddenly I find I can get other credit (I refuse, that's just me) and above everything, I feel like I have rejoined the human race and there are people who believe in my potential.
(I do work fucking hard though... )
Don't waste time arguing, your DH is not wrong in his reservations. Find a course that inspires you, talk to the staff, then take your case to your DH once it's watertight and you can show quite happily why it's worth the credit investment. x