As someone from a non-affluent background who made it into the legal profession via a history degree, I agree with the very good advice given above. Study a thing that you really like. Don't worry about monetising the degree. I am of the lucky generations who received fees and grants for university, but the student loan is, as noted above, in reality a tax on those graduates who earn above a certain amount, and paying it back is not a big deal for a person in a professional job. It's not like student debt in the USA.
A cautionary note: the legal profession has never been easy to get into (save, back in the day, for the children of lawyers, before meritocracy became the norm), but right now the profession is bonkers hard to get into. There are too many people chasing too few places. This is not to say don't try, but have your eyes wide open about the chances of success, and have a plan B.