Got a link to a guide? All I am wanting is root permission, no fancy roms or gubbins.
Used the Windows fast boot drivers from here (if you're using a Mac or Linux you don't need these):
http://forum.xda-developers.com/showthread.php?t=1997227
Then I ran the file here once I entered bootloader mode (hold volume down + up + power switch and it will reboot into bootloader mode):
http://forum.xda-developers.com/showthread.php?t=2003938
Short guide of what I did:
1) Download the Windows fastboot drivers (Nexus10RootNew) and bat file (r1-nexus10-superboot) from the two XDA links onto the PC and extract them
2) While unplugged, hold down the volume down + volume up + power button on the Nexus 10, a few seconds later it will reboot into bootloader mode
3) Plug the Nexus 10 to the PC, use the USB cable suppled to ensure nothing goes wrong
4) Windows will now complain it couldn't find drivers. Go to device manager, find the device, right click, update driver, then go to the Nexus10RootNew folder and then select the usb_driver folder, the fastboot drivers will now be installed
5) Go to the r1-nexus10-superboot folder then run the super_windows.bat file. Once it's done, the Nexus 10 will then reboot, and will be fully rooted
With this method your Nexus will not be wiped since the bootloader stays locked, and should also mean you'll still get OTA updates.
After playing around with it a bit more, Android System is no longer the big battery sucker. It's now the screen

. Charging seems better now because of it, must've been some google services doing some crazy stuff in the background. There also seems to be a few apps incompatible according to the Play store such as TVCatchup, but after extracting it from my phone it works fine.