I'd go attic, much easier to get rid of heat (which rises naturally, attic) than put in custom ductwork to heat a crawlspace (as well as totally bugproofing, disinfecting, and trying to put a cleanroom environment in such a small space) That said, there's a few issues with the attic idea too, but the attic would generally be much more secure than a crawlspace, and you may/should have higher clearance for bigger plants.. which opens up more strain selections to you that you wouldn't have to dwarf to make work in the big picture.
Tips:
Work with soil first, unless you have the $, and want to experiment with hydro. Soil will give you a firm grasp on horticulture and how to approach the cannabis plants, how to handle their needs, and wants.. and if something goes massively wrong with nutes, the soil has a bigger buffer than what hydro does. I may get flamed for this, but until you have a firm grasp of the strains, what you wish to grow, and as I mentioned.. get hands-on with them enough - do not start your plants in miracle gro - some of the time release fertilizers can and will bbq plants.
Learn what nute deficiencies, nute burn, nute toxicity, and nute lockout are, and how to correct them (there are more than a few fixes for some of the conditions that you can get much cheaper, or may have laying around the house or kitchen, as opposed to paying top dollar in a hydro store/greenhouse for them)
Obtain a pH meter and a hygrometer, or at least pH strips or and a hydrometer.
Read, and fully understand how genotypes and phenotypes will ultimately affect your plants, and how changing conditions will affect your grow.
Research: bulb types, bulb reflectors, best reflective materials for your situation/grow room, common pests that can wipe out your crop and how to fix the problem.. how to sterilize soil, how to sterilize pots ..
Ask questions! We all started somewhere, with minimal to no knowledge (even if that was before some of the RIU members picked up degrees in horticulture) - we're here to provide help to the community as we can, so as long as you can provide pictures of your problems, with an explanation of things leading up to it.. pH readings, water pH, etc.. we can guide you in the right direction to make sure your first grow is successful.
Hope this helps,
Fi-