Oy i'm back. I've got another question. I was talking to one of the guys at the local Ken Stanton and I asked about jack plates and if they were absolutely necessary, he said "No, as long as your wiring is grounded somewhere else, like to the bridge". I've only ever heard of grounding/earthing to the bridge but is grounding to the jack plate an option? Could i ground it to any random bit of metal, say a embed a nail or screw into the electrical cavity, could i ground it to that if its not touching any hot wires?
It's not so simple to give you a yes or not.
1) Jack plates are not necessary, regardless of grounding.
2) connecting the ground of your wiring to the bridge will NOT ground your wiring. Connecting the ground of your wiring to the ground of the jack (sleeve) will ground your wiring (i.e. will connect the ground of your wiring to the ground of the amp or pedal).
3) the bridge should be connected to the ground of your wiring, so that the bridge is grounded. The bridge do not provide grounding per se.
4) Using a random piece of metal will not ground your circuit. You need to connect the ground of your wiring to the ground of the amp/pedal (like in point 2 above)

Any question just ask
Just remember what grounding is, as a rule of thumb. Getting to ground. The actual earth, the ground, the dirt. You can't do that with a random piece of metal in the guitar. It has to follow the chain out of the guitar and out to the ground through the amp. And even then the circuit the amp is plugged in to might not even be properly grounded!

But if you make sure your guitar is, you've done your job, as I see it.
THANK YOU, dear GOD! I asked this on Alembic boards as well and i got a gigantic novel sized reply going completely around my question. This helps alot
I think some people simple don't understand the simple electrical concept of grounding. They have a misconception and it just festers misinformation.