1) Very often the right front headlight flickers out when driving. Will always work again if I turn off and then on again at the stalk. Once this has happened to the left headlight too. Once a blue moon a warning light will appear on the dash.
See if you can clean the contact points on the bulb and the wires. (clear if of any dirt and make sure the pins are making contact.
Use a multimeter to check for 12V
Also, if that fails, try new bulbs
2) Car alarm goes off about once a week/fortnight for no apparent reason. I have tried disabling the volumetric protection. The alarm still occasionally sounds, but now instead of sounding for the full 26 seconds, it will sound for only 2 seconds or so.
NO idea, movement?
3) Rear boot - usually takes multiple presses of the remote control button to get it to open
can you hear it trying to disengage the boot hinge? or no movement at all?
4) Air conditioner randomly turns itself on.
this is automatic, normal
5) Occasional the VDC / hill hold mechanism will fail, with a warning light appearing on the dash.
this is indicative of an injector wiring problem.
usually injectors 1 and 5 are bad.
similar deal to the headlights, clean the connectors. you might want to get an auto electrician to re wire them, or you could do it yourself
6) Cruise control occasionally fails, so that even if I flick the on switch on the stalk, the dash light won't turn on and the cruise control won't hold the car speed. Will work again if I turn off the car and remove the key.
7) Drivers side heated seat doesn't work, and passengers side occasionally won't (does most of the time).
^never heard of these 2 issues, sorry