I know a chap who 'retrained' into IT and was employed by my previous employer. However, that employer was modelled after the dotcom types, so they had lots of little empires filled with staff who surfed the web all day. Nowadays things are different and you might find it harder to get the break.
He was an ex-lorry driver, so don't think for a second you can't do it.
I think the best bet for you is to enter the industry in a support role (eg maintenance engineer rather than phone-monkey) and big up your customer-focussed, customer-facing, communication and organisational skills.
I doubt a degree will help, proven work will. A vocational training certificate will likely be much more useful as they have much more practical orientation whereas a degree can say 'you can pass exams', or 'you like to hide in academia' and says nothing about your ability in the real world.
If you have code examples (open source projects need your help and that'll look good on the CV) then so much the better, but be open and honest and explain that you like coding and that you're coming into the industry to get a job you love rather than coming in to escape a job you hate.
We also had someone who joined us from his own business, 2 weeks later, he just decided not to turn up anymore. Think of that role-model and explain to your prospective employers why you wouldn't be like that, 'cos that'll be one of the things they'll be thinking about.