Im thinking of making my own recording studio?

Okay well,
I'm currently 12, so this may sound a little crazy, but yeah.
I'm thinking of making my own recording studio in my house.
I currently have a Keyboard and a Tenor Saxophone. ( Really random I
know )
Anyways, Soon my dad is buying me an acoustic guitar and then a drum
kit for christmas. I'm also getting a good quality microphone and
headphones.
So, I was thinking, when I have my guitar, drum kit, laptop, music
software for my laptop, and Mic and Headphones, I would make a
recording studio in my house.
But, What else would I need? And how much would it cost?
Oh and, I know this is really random, but I'm excited cause I'm
performing at the Sydney Opera House next month, and it'll be my
second time. :D, Just thought I'd share with you all. Okay well yeah,
What else would I need and How much would it cost?
Thx
xx