That's the deal. Choose a /home space big enough to store your data,
settings etc. You will need to make allowance for your habits. For example
if you download torrents (or anything P2P), it will keep partial downloads
as well as completed ones. These can add up. You can move completed ones to
the Windows host (C: drive) and that will free up space. You can clean out
your caches at regular intervals but if are lax they too can add up quickly.
A good utility to install is filelight which graphically shows you what is
using the most space. It is in the repositories.

I have found Linux very forgiving, but it can become unstable or even fail
to load if you run out of space in your drives.