Plz help

So I’m 16 and live in Manchester in England. I love acting and performing arts and for college I wanted to apply to a few to do performing arts, I looked at a few and didn’t know which ones were for me until I came across one last year called the BRIT school. it specialises in performing arts and technology and I spent hours looking into it, looking at what other people thought of it and stuff like that. But it’s in London, the south of England Manchester is in the north, it’s a problem.

I knew it would take a lot of convincing my mum to let me go there or to even apply but I wanted to see what she thinks. So I asked he out of the blue if she would ever let me go to a college far away like London for example. And she said yeah, it came as a shock to me. I asked her again just to check that if I wanted to go to London for a college she’d let Me? And she said yeah. So that was it, it was locked that she would let me if I wanted to.

A few days later I messaged her and said ‘I’ve found a college I want to go to, it’s called the brit school look it up’ and she said ‘no. It’s in London’ and my heart shattered. It’s something I’m passionate about and when she said I could it instantly got me excited. She was sticking by that she didn’t want me to go and that I couldn’t.

So I applied anyway, just to see if I would even get an interview/ audition. It was probably the best thing I’d ever written because I got an interview.

For the interview I have to go to London and perform 2 monologues, which is fine with. But my mum doesn’t even know I applied and if I tell her I did it behind her back she will literally kill me. So the interview is in 3 days and I’ve planned to get a bus down there and back so I can do it, I asked my brother if he wanted to come with me and he’s almost 18 so it won’t be as bad as me going alone. He’s still really confused and hasn’t said he will or won’t yet. But I just know I need to tell my mum because I’ll be missing school that day, leaving my house at 4am to get the bus at 5:30 am to get to London at 11 am to go to the interview and then get the bus back at 6pm to get home at 12:30 am. She will 100% know that’s somethings going on. How can I tell her?