If you cover up all light sources in the loft, (e.g. windows & skylights), and leave the hatch open, and if it's left undisturbed it'll come out of the hatch. Again, cover up all windows except for one that you leave open, and it'll go free
keep a window open.....try and throw a towel at it and capture it in a towel. If it got in then it will get out (I presume a window?) if so open the window and go away and it should find its way to freedom.