My small stealth grow box, going to grow one plant and lst it

since my space is quite small i am only able to grow one plant, i am also going to lst it as there is more width rather than height in the grow box, it is yet to be painted white inside or foiled, and my lights and fan need to go in there, here is a pic of the box though, i have used this black felt stuff used to waterproof the outside of a shed, i have used this to stop light escaping, its a stealth box in one of my dads sheds that never get used, it has electricity in there etc so im all good to go, here is a couple of pics..,





in the bottom right corner there is a little pipe i used it off an old vacume just for a bit ventilation, i can feel nice fresh air coming inside from it.. im a little worried about the temp in there though, its only like 6 degrees and our winter is due to get colder and i am only using a couple of cfls. i am thinking of putting a small heater in there or putting some normal lamps in there just to provide a bit more heat, i am not gonna face them towards the plant i just want them in there to perhaps provide heat, let me know what ya think