Ive searched and im a pretty confident i know what i have to do to fix the problem, but I just what a "thats right" from someone who knows what there talking about.

My BCM is playing up, and nearly every time i want to start the car I have to smack it round the dash where the BCM sits.

I played with all the plugs but it doesnt make a difference, so it looks like maybe something internal is breaking.

If i replace the whole unit with one from the wreckers. And i make this BCM learn from my keypad, does this mean my keys will automatically work? or does it just make the keypad work with it?

If i have a fairmont but can only get a low series of mid series BCM is this okai?

and you have what model car?

from memory, you will need to do the complete relearn procedure for it to learn your keys.

I have an EF.

What do you mean complete relearn, is that the leave the keys in for 30 mins thing?
Also im finding it hard to find a fairmont one (green colour) can i use a lower series one.

you need to program in each keypad you want to use!

yep!
Just Relearn the Ignition Barrel, (30mins) and each Keypad.
Very easy.

If ya close and need help I'll put an offer in.

its okai, done it all. Thanks for the help guys.
Picked up a high level (green one) from the wreckers and put it in. Works perfect now.

Now im gonna find the dry soldier joints in the old one and fix it up then sell it off.

If your problem was just that the car wouldn't crank, you could have just had a faulty on board relay.

Connecting the starter relay coil positive to the ignition switch crank positive would get you out of trouble temporarily.