Resit of gcses

Hi so I live in the UK (near ish to London) I'm in year 12 and I had all sorts of problems with my health which meant I failed three of my gcses which means I can't get into sixth form. I decided on taking a year out so I can study and redo my gcses in the summer of 2023. Does anybody know where I redo the gcses and which exam boards? I did OCR for my school but would rather stick with AQA? Thank you

If you're resitting your GCSEs, you would usually need at most 5 at good grades to get into 6th form (don't go crazy and resit all 9-10 of them). I would also check the entry requirements for the specific 6th form that you want to apply to, as well as the courses that you want to apply to.
The 2 essential ones that are asked for in jobs, university, and 6th form are English Lanaguage and Maths. These you can resit for free through an adult or vocational college near you. They usually require you to spend a year to prepare for them.
However, you can also resit them via an online college (for course material) and applying as a private candidate (for the exam). If you really want, you can also buy the necessary course material, study yourself, and apply as a private candidate.
Where possible, I would try to resit the GCSEs for free.
The other 3 subjects will depend on what you want to study at 6th form and what you find yourself excelling in. I would look at the entry requirements (which I find are a joke because there are no official entry requirements for any A Levels set by any exam boards) for the specific A Levels at your chosen 6th form college. If the college is asking for a 6 in Biology for Biology A Level, you would be keen to resit your biology GCSE if you don't have the grade for it, as an example.
To resit these 3 GCSEs, you would likely need to either self study or go through an online college before applying through an exam centre. The good news is that as a free agent, you can choose any exam board that you want, be it AQA, EdExcel, or OCR. There are no restrictions per se, but if you're going for an online college, you would want to pick a course that teaches in the exam board that you want e.g. if you want to resit French with AQA, you would want to find an online course that does GCSE French with AQA as opposed to GCSE French with EdExcel. The forunate thing is that most online colleges offer courses in AQA (I don't think I have to try too hard to figure out why), so that works in your favour.
I don't recommend resitting GCSEs that have a lot of practical elements to it, unless you want to do it at A Level and the college requires you to have the GCSE at a certain grade before they let you study it. Subjects with practical elements can cost a bit more to assess and may require you to do a lot of preparation e.g. the sciences, languages, design tech. Theoretical subjects often are easier to handle in terms of assessment and logistics e.g. business studies, history, literature,
To apply for the exams (do try to do this in advance e.g. before February), you will have to go to the exam board's website, go under private candidate, and look for an exam centre you like (ideally one nearest to you). Contact the exam centre and liase with the exam officier there. You will be asked a number of things to fulfil your application, as well as the fees that you will need to pay. The fees are set by the exam board, but you pay them to the exam centre.
Between now and the time of your exam, study and revise like crazy. There are no shortage of YouTube videos and websites that you can look at to go over specific topics, get advice on study/revision, or go through past papers. Past papers being crucial for exam success.
I would also recommend looking at revision guides and exam practice books (unfortunately most of them will be by CGP). Use them to good effect for your studies.
Let me know if you have any specific questions.

Hi I didn't do too great in gcse maths and science( I didn't fail I just didn't meet the grade requirement by a lot) but I really want to do a level maths, further maths, and physics. I'm planning to do a btech this year alongside redoing my gcse maths and science, and next year I'll apply to a college to do maths, further maths, and physics. I'm confused as to how resitting works, so do I just apply as a private candidate on my exam boards' websites and pay for the exams and do I have to go to an exam centre because the prices are quite expensive and I can't afford it, can't I just sit my exams in a local college/sixth form or will I have to pay them?Also do I have to apply for an online college or can I just study by myself and go in to do my exams. Sorry I really need an in depth explanation for my situation.