Repartition Dell XPS13 with Ubuntu 12.04
That is the standard Ubuntu partition Layout, there is no hidden restore partition like you can get with Windows systems. You are safe to repartition after backing your data up.
You can easily create root, home and swap partitions from the Ubuntu installer, just selected the advanced options, official help:
https://help.ubuntu.com/12.04/installation-guide/amd64/module-details.html#di-partition
You don't need to keep any pre-existing dell partition if you're not using windows, so feel free to use the entire disk.