More than enough on the provision that you do not use too much space for
saving large multimedia files. You can always save them to your Windows
drive as your home partition fills up. You can install everything but the
kitchen sink and still use just over 10 GBs.

I would not depend on WUBI too much. It is a great way to introduce a person
to Linux, but it is a large file(s) and as such it is subject to being
damaged by hard boots, crashes and viruses. You might want to consider
creating a partition and backing up your home folder to it using a utility
such as BackinTime. That way if WUBI gets damaged or even if you want to do
a full installation you can use the backed up home and copy data back should
you need to re-install or choose to do a full installation.