I dont work in cyber security at the moment but I do taking part in security projects in my job and I have a few cyber security certs.
As cyber security is so broad such as defence, ethical hacking, on-prem, cloud security, etc. You need to decide where you want to be.
Understand the basics of security and get a certification such as Comptia Sec+ (doesn't seem useful in the UK) or Cisco Certified CyberOps Associate, maybe even an cloud security cert such as the Microsoft Security, Compliance, and Identity Fundamentals (SC-900). The CyberOps Associate covers abit more than just cyber security but an overall picture such as networking, DevOps, info sec etc. You can buy the materials, take the exam and see from there. Self study in your spare time, dont bother attending courses or anything.
CISSP is more for information management than cyber security and there is an requirement for taking the exam which is an high level.
Work on a few projects off the internet
https://www.techapprise.com/cybersecurity/hacking-learning-websites/ and build a portfolio. Combined with an basic cyber security cert, this will help you get your foot in the door which you start applying for jobs.
Keep in mind, some JD's have crazy requirements, even for juniors. Ignore them.