Graphic Design Diploma

Hi, I am sorry if this question is too basic one, but I am stuck to fine right qualification (diploma or certificate) for getting a job.
I have learned graphic design more than 2 years by myself (not full time, Because I have a small child) And have sold my designs few times from competitions.
I would like to get a job now but when I check advertisements, most of company look for someone who have design qualification. I know a design degree is best one for putting my CV but I don’t have time (4years) and money for that.
However, I would like to get a diploma or certificate for putting my CV. So can anybody recommend me which qualification is best? Thank you.

Depends on where in the world you might be. What country are your seeking work?

Oh, sorry. Of course, I live in the UK. Thanks.