Expand the disk in esx
Take a snapshot
Refresh disk size
echo 1>/sys/class/block/sda/device/rescan
if you fdisk /dev/sda you should get an error like GPT PMBR size mismatch (2147483647 != 4294967295) will be corrected by w(rite).
fixed with sudo parted -l
Then follow this:
https://askubuntu.com/questions/24027/how-can-i-resize-an-ext-root-partition-at-runtime
df -h to verify that you've got the more storage
Delete your snapshot
Crack on with your holiday (because systems always run out of space when you'd like to be away from your computer).