The installer for whatever distro you choose should handle that for you, but you should create the partition yourself, as long as you have enough free space and the partition is < your free space you'll be fine.

 

Just be careful to install to the correct partition. If you install to a partition that's in use, then data will be deleted.

 

I think 8GB is very little space, but it should work anyway.
Only later, when you run out of space you will get angry.
And if you start getting various packages for experimenting with development that will happen at some given point for sure.

That said, with which programming language do you plan to start?
Learn to use git early, it comes in handy.
Perhaps try first learning something like Python first, it is well documented and supported by the comunity, it has great style, it should be easy to learn and it would probably teach you some good practices.