No qualifications are required (which is the question you asked) - this is not a regulated industry.
Some qualifications might be useful, to answer a question you didn't ask, in competing with the other suppliers out there.
I once ever got a job because I had a qualification that the other guy on the shortlist didn't have, and it was otherwise a toss-up between us (or so the TD told me after I'd started in the job). But for the freelance work I do now I rely mostly on reputation, with the CV on the web site for anyone who doesn't know me. Mostly people care about whether you have the practical experience and prefer someone who knows what they're doing to someone who has passed a few exams.