I think it would be a good idea if you told Exeter about your extenuating circumstances. If you have already sent of your UCAS application, find someone who knows what you were going through and get them to submit a second reference via email to Exeter explaining your GCSEs. I did this (and I had much worse GCSE grades than you) and I got into every university I applied to. I think it is worth applying now, if they say no then you can redo your IGCSE.