The time, money and effort you spend converting an attic into usable state (not to mention the necessary acoustic treatment) is so enormous, it could turn your bedroom into a respectable home studio. Besides unbearable temperature, animals may crawl into the attic from the roof. You don't want your cables and equipments get destroyed by half a dozen of squirrels, right? Think about it, if the attic was a feasible idea for a studio (or anything at all), the term "bedroom musician" would be obsolete