So in terms of courses (I'll try to provide all the free/cheap ones that are from reputable places)
Coursera - AI for everyone - this is a pretty solid first place to start 6 hour course that's free and by the creator of coursera, and should give you some more ideas of where to go next/focus your learning as it's non technical and aimed as an overview of AI and it's possibilities
Coursera IBM - Applied AI - there are more 'official' coursera courses with certifications, there are quite a few, but industry sponsored ones are best imo. There's also Google certified ones on coursera and Amazon. There's ones from universities too as well as online masters delivered through coursera, but I think if you aren't wanting to do a masters then the industry certified courses are better for employability than the shorter university courses as the industry ones are much more applied and you will produce some of your own work as part of it. I find the none masters university coursera courses are more theory based/harder to practice. There's also a ton more free courses on coursera that it could be worth you doing before committing to pay as you might find you want to specialise in say machine learning and then a more specialise certificate course could be the way forward. I believe they also offer to cover funds for the paid industry certification courses if you're unemployed for the industry certified AI specialism courses, I think you have to apply with how it will help you and that you are committed etc.
https://ai.google/education/ - google have a shit ton of free courses, guides etc.
https://www.freecodecamp.org/learn/ - there's a ton of free learn to code resources, including game based learning etc. but I've found this is my favourite. They recommend you start with web coding languages, but I think for AI focus you could start with the 'scientific computing with python' if you really just want to get stuck in and then pick up tools such as visualisation later.
There's also UK Government skills toolkit with links to various AI courses (all free) - https://theskillstoolkit.campaign.gov.uk/
and the Institute of Coding has a mix of courses and guidance too - https://instituteofcoding.org/
There's also specific courses out there depending on what you're interested in with AI. E.g. there's a really well rated one for AI in gaming AI for gaming sector
Once you learn python then there's tons of cool online resources to practice and play around and learn and build stuff - e.g. https://gym.openai.com/
In terms of masters in person at UK universities then the government worked with higher ed to create a conversion masters for AI. I believe they have scholarships for people from underrepresented groups, else they can be really expensive. Here's more info. https://www.officeforstudents.org.uk/for-students