How can I tell how much disk space I am using please?

You should clean temp and set it’s size.

You can check how much disk space you are using by running the df command.

root@droplet:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1        40G  3.9G   34G  11% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            999M  4.0K  999M   1% /dev
tmpfs           202M  324K  202M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none           1008M     0 1008M   0% /run/shm
none            100M     0  100M   0% /run/user

The -h option is used to output human readable sizes (e.g. 34G instead of 34000000000 bytes).

In this example, the droplet is using 3.9 gigabytes of disk space.