Most schools and universities allow GCSE students to re-pass exams. You can retake the English and Math exams in November and the exams for other subjects take place in the following June. You will need to check the exam schedule with your school again. You can still register to retake your GCSE at a local school or university.
This means you'll have a schedule and attend classes with other GCSE students. Once regulations have eased around the current pandemic, you should be able to reinstall your GCSEs in one of two ways. You can reapply at school or university and study together with your AS levels or you can re-apply as a private candidate and attend an online course. Remember that if you have failed English or mathematics, you will have to take them in school until the age of 18; however, in order to re-submit your GCSE, you can study as a private candidate if you are under 18 (or if you have passed but would like to improve your grade).
For example, if you're good at English, you might want to study careers such as journalism and marketing, as these professions value strong writing skills and often prefer candidates to have valuable work experience rather than university degrees.