Hey don't let it get to you. You can absolutely get that grade up to a 6. Maths is hard and we all have bad days, but if you really work on it, and once you've had a little time to process the grade and form an action plan this is totally achievable. I know how soul crushing it can feel to get a result you weren't expecting but you still have A LOT of time ahead of you. I'm not saying work every day of your summer holiday but once you've had some time to process things go through that test. Make sure you understand where and why you went wrong. Over the summer maybe put aside an hour a week to focus on topics you struggle with. Trust me, this will be a lot more than other people your age will be doing. You can do a bit more than that if you feel necessary but please don't overwork yourself. You don't want to feel burnt out before year 11 has even begun. I'd recommend gcse maths tutor youtube chanel and Corbett maths and maths genie for past papers too. I learnt so much in year 11 as well so really don't panic you have lots of time ahead of you. Make a bit of you time and try to come to term with what's happened then form an action plan. If you use the next few weeks wisely you can definitely get that 6 if not higher. Best of luck.
Caotica