Hi Kristian,
(I'm sorry that no one else has replied to your question.) Five years ago at the age of 51 I began studying for an MA (part time over two years) in history, at a university in the midlands (and am now doing a PhD, also part-time). I saw the MA course advertised, and e-mailed the professor who ran the course. We then had a chat over the phone, and he was very happy to let me onto the course. I had a 2:1 BA in History of Art taken 28 years before, but he also admitted a chap aged 60 who had left school with only O-levels, but who had since undertaken some significant local history research. The point is that it was very much up to the professor to decide whom he admitted to his course, whatever their academic achievements.
So I suggest that you firstly look at the MAs that are available in subjects that interest you, and then e-mail the professors of a few to find out if they think you are suitable and whether your degree is sufficient to let you in. If you are keen enough then they may welcome you with open arms.
Best wishes,
William