Homeschooled and taking GCSEs at a new school

I’m rlly nervous bc they will be in uniform and I will stand out. Also I’m scared of having to go in by myself and just don’t wanna embarrass myself. Also I’m obviously not allowed my phone but I need to take in with me bc my mum has gotta pick me up and I don’t wanna have to get kicked out or something . Also bc I have no phone I’m just gonna be standing in there awkwardly and it just sounds like a nightmare . I’ve spoken to people and everyone doesn’t get why I’m stressed but I over think like this all the time. And was wondering if it’s as big of a deal as I’m making it out to be or if im overthinking it. Thank you