Did a few clinician surveys and patient interviews to supplement a SLR (focused on economic issues, almost no medical info), consent forms were all completed but forgot the ethics review application🤦‍♂️.. supervisor hadn't mention it either. Will I be auto failed?

I don't think you will be auto failed or kicked off your PhD but it is a serious issue. I would definitely tell your supervisor and stop the data collection/analysis for now. Ethics boards can be a pain at the best of times and you don't want to make things worse. Although you may be able to get post approval but your supervisor should be able to give you better advice.