In case anyone is interested, here is a two-week follow up.
I swapped the plants around, following the discussion here, so I now have the following under the lights.
Nepenthes Bloody Mary (x2)
Heliamphora heterodoxa x minor
Heliamphora minor 'Auyan Tepui'
Drosera Aliciae
Drosera Madagascariensis
Drosera Nidiformis
Drosera Spatulata
Utricularia Longifolia (sitting next to the water tray, as there isn't room for it directly under the lights)
In addition, I have two pots with some of the VFT leaves that I shredded from a B&Q rescue. Although they would normally be going out in the cold, I decided that as they had roots, and so were worth potting up, I'd trying keeping them inside this winter, as the shock of being sold in B&Q (pretty humiliating for a plants I reckon), then being bought by me (ditto), being pulled out of its compost, being ripped to shreds and then being repotted was quite enough for one small plant! As I'm hopelessly new at this, I can happily ignore the rules and write it all down to experience!
Anyway, it looks like the experiment is working. Although the Drosera Aliciae looks like it's drying up, carni grower assured me that this is normal, and it does seem to be going red. Even better is the Drosera Spatulata, which retained its dew, and is going even more red...
Both Nepenthes Bloody Mary have leaves that are turning red. I'm assuming that this is a good thing, although most of the pictures of these I've seen showed them with green leaves, not red. However, they look healthy, so I guess it's a good sign...
Finally, having added my two ha'porth (old Yorkshire expression for "small amount") to the discussion about propagating plants by immersion, I decided that as my office is warmer than the kitchen (stays around 22-23 degs C during the day), I would move the immersed VFT leaves under the lights, as they kept getting moved around on top of the turtle tank. I came up with a fairly ingenious way of storing them...
I've done this on both sides, so have about 16 test tubes under the lights. I will be interested to see what happens to them. Two of them (from before the B&Q shredding exercise) already have small plants growing, so I'm hoping the others will follow suit.
Hope this is of interest to someone. It's been good fun, and a fairly cheap way of experimenting. I'd highly recommend it to anyone!
Ta ra