Olea Europaea planted outside?

Only plant into the ground if you have very free draining soil that is not too fertile. It would need a pretty sheltered position in full sun to do well and just so you don't get your hopes up you are pretty unlikely to ever be able to eat any olives from it.
I would not plant it now but wait until next spring to plant it out so you know it has hardened off reasonably well. Chances are the place you purchased it from would have raised it in a heated greenhouse or their supplier did.

Many thanks for info, will winter in greenhouse