The key difference between hobbyist and professional web development, in my opinion, is not so much programming knowledge but rather knowing the tooling that surrounds a project (git in particular, testing rigs, etc) and learning to work as part of a team (how to estimate work, what to do when you blow up the git repo, etc).
On qualifications - there's companies out there that insist on some sort of qualification before they'll go further than your CV. There's other companies that care nothing about such paperwork, but want to hire people who are good at solving problems and eager to learn (quickly!) from colleagues about all the stuff needed to do the job beyond the code base itself.
PS: don't leave the career change too long - ageism does, sadly, exist in the tech industry. It took me over 800 applications to land that first gig!