GCSE exams are usually over by mid June. My dd had her last one on the 13th (out of 21 exams ) this year. Some doing additional maths had their last one on the 16th of June. It's more than likely that she will have had her last exam by then.
It looks like she may have her final exam - a DT paper - on Monday 22nd. Her teacher did say it was one if the last papers that they sit. It's her favourite subject so she will be well prepared and not trying to cram two years worth of knowledge into her last revision session
Maybe I was hoping it would be me that could relax