So you have installed ubuntu inside windows and due to maximum size of 30Gb restriction you are worried then let me suggest you an option to get more space without formatting or reinstalling the ubuntu.. here it is
when ever you are installing any new software, or need to store some file just create on folder in /host/somefolder and start putting your files here, since this is the drive where you have installed the ubuntu it will have all the space available in C: or what ever drive you have installed ubuntu in. and you can use this space for what ever you want.
So Simple and easy solytion right.... :)
