Check out this free room arranger software. (It's actually an older version of a pay-for program that they release as freeware
. You can get the typical 30 day free trial of their current 'full' version, too. The full version is only $20!) http://www.roomarranger.com/index.html
The newest freeware version is 3.26. (I haven't used this version. You may want to check the 30 day trial versions, too. You can download 3.26 and other versions near the bottom of this page: http://www.roomarranger.com/whatsnew.html#downgrade
I used a trial version (probably v 3.61) to lay out my new flat, including a small studio room.
Since I was moving from nearly 1500 sq ft into just about 400 squares, there were some, shall we say, challenges
. But I was able to figure out precisely how to arrange my furniture to make the rooms work. On moving day, everything went straight to its spot in an orderly fashion and stayed more or less precisely as I laid it out for a year and a half. (I did experiment with moving things around, too, but I always found that the way they worked best was just as I'd laid it out staring at the computer screen 6 miles away.)
It wasn't super sexy, but it worked quite well.