I don't have a "spare room" so I have to make use of our dinning room. Its a got a good sized table and lots of natural light coming through we just can't use the table for eating from as its normally got something fabric wise on there but my DH doesn't mind at all.
I had thought of moving out into the garage, but then I remembered how cold and dark it would be in our long winters, so I'm staying in the dinning room.
Hope you have fun arranging your new studio.