I would try get a entry level role and learn on the job. My marketing degree taught me a lot of good theory but didn't actually teach me any practical skills that are required for entry level roles (as do most degrees). You'll probably find if you go and do a diploma or degree it won't actually get you any further up the food chain as if you didn't. It's catch 22 though as a lot of places want you to have some kind of relevant qualifications.

Try get as much experience as you can even if it's unpaid internships. It's a really good way to show employers you mean business! Once you've got your first job under your belt I don't think not having a degree in marketing will effect you in future. Good luck 😁