Space heater, good idea. Especially if you get one that can be a cooler in summer too.
That 24-70 lens. Why? because it is probably magnificent. Why not? Because f1.8 and f1.4 are more useful than f2.8 for focussing, though much less useful for portraits. Because having 2 smaller primes includes redundancy, one can fail and you can still use the other. Because you already have 50mm covered I believe, so need the long end much less in your smallish room. (btw I suggested 2 lenses, but anticipated you only buying one of them.) Because zooms rarely, if ever, give as good results as a prime in the same price range, or even much cheaper primes. And there it is, my main misgiving – that 24-70 mil lens is 2,000 dollars. That’s really splashing out at an early stage of the career path. Buy it when the business has earned it, not before. (I had a DTP business years ago, complete with a laser printer worth about 2500 dollars. I gave really great product. I sold about 1,000 dollars worth of product in the first year… Lost more than that on reselling the printer at the end of the year, having learned that I was a poor businessman.)
You are using the biz to subsidise your dreams. If that lens is the dream, and you can afford it, buy it. But… 2k dolares! Ai caramba!!