Damn, I've got some bottles of 18mg that I could organise for you but unfortunately no 12mg. The 18 is a few batches old o it may have weakened over time though or could be heated to drop the nic?
Are you gonna use it with the twisp battery? They only output about 3.3v from the ones we've tested. Why not get her something slightly more recent to ensure its serviceable for longer.
We stock the coils too. Unfortunately not the tanks but if you need spares for the tank I have a whole bunch of ones that were returned for various reasons that I can give you parts off of.