I have been asking my mum to get me a kit, but she keeps on saying no, and it’s really frustrating

Ugh, that sounds super frustrating when you know what you need and your grown-up isn't getting it. I totally get it. Sometimes grown-ups just need things explained a bit differently, or they don't realize how important something is to us.

Maybe try talking to her again and explain why you want a period kit. Like, is it because your friends have one and you don't want to be caught off guard? Or because you want to feel prepared and grown-up? Sometimes explaining the why helps a lot. You could even show her some period kits online or what you'd put in one, so she sees it's not a big deal.

Another idea is to offer to help put it together. You could say you'll help pick out the stuff or even use some of your allowance for pads or whatever you need. That shows her you're serious and responsible. If she's still saying no, maybe there's another trusted adult you could talk to, like an aunt, a grandma, or a school nurse. They might be able to help her understand why it's important.