Retaking a level comp sci

Well I flopped my results and will have to take my a levels again, I had some personal health issues and I don't want to go to my insurance, there's 2 questions I gotta ask: will I be at a disadvantage with top unis if I retake a levels, and since I'm taking a level comp sci OCR again will I have to submit a completely different piece of coursework or can I resubmit/ edit coursework

I also flunked A Level Comp Sci OCR, I hated it so much. My other two were alright and I'm doing a foundation year.