Seems your in the uk as I am, I would recommend n Bill Bailey to stay with, this had been made for growing on windowsills in the northern hemisphere. I have been growing this from a little 3inch plant in a bio-dome in 2011 or 12 to a nearly 4 foot vine that flowered this year.
Here's an intermediate pitcher
Ams a lower
And the whole plant
You can get a small plant of this from asda in a bio-dome, don't know if they still have them but worth a phone call. If not I have one that's 10 inches from leaf tip to leaf tip that I could part with. I also grow on the same SE windowsill, robcantleyi, tentaculata, glabrata, lowii, spectabilis, fusca x robcantleyi, ventricosa x rob, densiflora x rob, aristolochioides, spectabilis x aristolochioides and x princess alongside my numerous heliamphora and section orchidioides utricularia,
Here's a pic of jamesoniana in flower at the moment,
All are just sitting on the windowsills in ambient temp and humidity, but I do live in Edinburgh!