Welcome, Termite!
Well, I do not know about UK travel, but my recent US travels yielded these tidbits (there are several air travel threads, be sure to read the new member info and search around some):
In addition to separating the battery from your mod, I would suggest a small label applied to it, and then packed in another clear quart sized zip bag - along with any other small electronics you plan to take in your carry on (do not pack your batteries in your check in luggage), including Ipods and the like. Placed appropriately in your carry on, it isn't likely to snag too many questions, if any. Your quart size zip bag of liquids goes on the very top of your carry on, so it can be pulled out quickly and placed separately in a scanning bin at the security checkpoint. Directly underneath your liquids bag, you need to have your spare shoes - if any - that you are taking in your carry on. You do not have to remove them for scanning, but do need to leave your bag open for when it is scanned in case the security folk want to look closer. Yep, your spare shoes will be on top of your change of clean clothes. Then, directly under those spare shoes, have your quart zip bag of small electronics.
Granted I use 808 batteries for the most part and they probably get the least double looks, but if everything is packed carefully with consideration for the security folks, there is much less chance of anyone getting suspicious of your gear. I traveled with two pcc's, 2 carry cases with 4 808's each, and two different usb/wall adapter charging units without any problem at all, packed in the quart bag along with my Nano and a hand held game. What really surprised me, though, was that I accidentally got myself into the line for the big personal nuke scanner (no one waiting in line should have tipped me off), and rather than collect everything up and go get in a different line, I went ahead and took my radiation dose - and I had an 808 in my front jeans pocket that I'd been using in the airport terminal to stealth vape and use in the restrooms. I just forgot it was in my pocket. And, no one said a word. No pat down, no sideways glance, just a "have a good flight," and I was on my way. As near as I could see, no one was concerned for my small electronics bag, either. (I wouldn't recommend the pocket pv as practice, though.)
With regard to cartomizers, I put them through with my liquids in their original boxes. No one seemed to care too much. I think I had three 5-packs with me, didn't take up a whole lot of room. I kept them in the boxes because what they were was clearly marked on the boxes, and no one so much as said, "boo!" about it.
