Which are the branches related with space.

Sounds like you're interested in astrophysics, which is a branch of physics resulting in a BA (or MPhys if you go for a Master's degree). This means you'll need very good maths and physics. Computer skills and chemistry would probably help, though I doubt they're essential. Most astrophysics courses are actually physics for a while, then you choose a specialisation. Professionally, after University, a qualification in astronomy will be very useful if you want to work/research in the astrophysics field - as will excellent communication skills. You'll probably have to do a lot of writing!