Actually, you do have a space for writing.
It's between your ears.
That's where the important stuff happens.
As for where you actually put down the words, J. K. Rowling used a coffee shop and she's done rather well.
Other options include a library, the lobby of a large hotel (act like you're waiting for someone and when you're done look at your watch in exasperation and walk out), the house of a friend while they're out (with their permission of course), the public area of any large government building or bank, an airport or train station, an internet cafe...you get the idea. Get a briefcase with sections so you can take along any paperwork or research.
Within your own home, you may be able to carve out a place inside a bedroom, or use the kitchen table, or a folding desk in the laundry room or in the garage. Or in the car parked in the garage.
Yes, of course a study lined with bookshelves would be nice. Nice but not necessary. Necessary is some light, a pad and pen and/or a laptop computer.
And your brain.
(My book, "Your Writing Coach" is another great source of excuses-killers. Get it from Amazon or other online and offline retailers. And for a monthly dose of inspiration and guidance on how to be more productive, sign up for my free Brainstorm e-bulletin. Just send an email request to [email protected])