I think you will be hard pushed to find an auto-rewinding unit that isn't mounted in some way as it will be quite unstable when it is fully wound out. There are a few like this which are neat but are hand wound http://amzn.to/2IBx2ly

If you have the option to wall-mount though this will satisfy your needs well http://amzn.to/2FOd3lP

 

If I remember correctly I came across a retracting Hozelock unit that can be hung from the supplied wall bracket and lifted off when needed somewhere else.
All of five seconds to lift it on or off.
When I get a moment I'll see if I can find it again.