Dean87

Left mine for 2 months. On re-connecting the battery everything came up as normal. No issues whatsoever. Remember to leave the boot ajar else you will not get back into the vehicle.

Thanks Alan.
Unfortunately I will have to leave it outside (on street parking). 

However, I did a quick test and you can open the boot from the outside, as long as you unlock the drivers door with the key (which releases all locks).
If you use the fob or touch to lock the vehicle, the alarm will go off when you open the door with the key (although if the battery is disconnected I believe the alarm is disabled).
But you can use the key to lock the car once you have disconnected the 12V battery.