right, mate its not about brightness, well it is but colour balance is the basic. it can be as bright as the sun but if its not inthe spectrunm of useable light for growing plans it just wont work. so buy bulbs for the job! check the ratings which are ritten on the bulbs. to get an understanding check out greenshorticulture.com or greenseahydroponics.com both have bulbs and advice. if you only want to use one light and get a definate crop, check out a strain called auto Cream Caramel. all autos only require one light(the fed one, flowering light), fuck all space and soo little nutrients its beautiful. they can be a little unstable but have only read good things about the CCautos! it may be worth the added risk and hastel of buying the seeds of auto strains as they will fit your room and energy needs, also they come feminized so no sexxing issues. but they wont clone, from cuttings, so back to seed every time. but you dont have room for mothers, cuttings and clones yet any way. also a cutting in rooting solution is a clone. a clone is a plant so 1 mother and 10 brances in rooting hormone, of which you may only use 3, still counts as 11 full plants! also the loacl indiginous herbs group up to 8 foot tall, could be a problem for you.
i think you should by compact red spectrum fluorescence (cfl red) from a regesterd horticultural dealer you will need 250w+ ( cfl 250w red) i would be tempted to 500whats straight away, more of the right light, more bud! mount them using a 'parabolic' style lamp shade, this alows the light to dangle in the middle of your plants, simply build a chicken wire case to stop plants touching bulb. its only a minor fire risk with out the chicken wire, but too many leave and the light wont reach the plants. but autos only grow to 3 foot so you may not even have that problem!
a small air mover is a must! can be a £1 job jst to keep the plants active, and your extraction whole should be larger than your in take vents! you can build a cheep carbon filter if you need to, out f duckting tights and charcoal, but buying one would be much better im sure.
im going to leave you with that for meow
peace