Addressing the question from this point:

>leading on to a career change into photography

A photography career is actually not really about photography, thats just what you produce. A career is either getting a job from someone else, in which case you need to have self marketing skills, networking, and get lucky, or it's about creating your own business in which case you need all the myriad skills, patience, fortitude, and good luck to succeed.

None of that is possible without good skills as a photographer but where you get those skills from is largely irrelevant and measuring the cost effectiveness of the learning proces is highly subjective.

Edit, wanted to add something about a degree: going to uni to do a degree gives you the opprtunity to meet and make friends with a group of people who will be your cohorts. Thats why the 'posh' universities are so expensive because you meet a more infuential class of people. Without that opportunity a degree is not worth as much on paper, particularly an arts degree, which used to be what kids did if they didn't have any other skills or interests (although I'm being a bit mean here I must admit)