Chinese Elm...Indoor or outdoor?

Hi everyone. I have 2 or 3 bonsai but I have never had a Chinese elm before
and so decided to get one. The one I bought seems to be very healthy and was
purchased from a reparable bonsai nursery. Anyway what I need to know is
this an indoor or outdoor bonsai. I live in England and at the store it was
labelled as an indoor bonsai and was kept indoors but I would like to hear
your experiences with these trees. Also as I understand it supposed indoor
trees are best left outdoors in the summer.

Thanks in advance.