Local 'walk-in' testing

Has anyone been to these centres and confirm whether I can actually just turn up or do I have to book online? Thinking of Peckham Pulse or Belair Park..

I've been to Belair Park and I believe you needed to book in advance.

I just tested this out and you can just walk in - they ask you to book online as you arrive using a QR code, but I don't have a QR code reader. They then gave me the test pack and the barcode and just told me to register it when I got home. This all worked fine.