I'd put it outside now the weather has warmed up, but it is frost tender in some areas of the UK so it may/will need winter protection.
it will grow into a tree [20m] in time.

You will need a tall coldframe then!

Thanks SBG and yorkslass, that was my first thought ,it maybe a case of indoors in winter and out in summer ,til it gets too big ,or i pop my clogs lol,then maybe a donation to our nearest botanical gardens :)

The frost doesn't bother it as much as the winter wet. I would look for sandy soil, in a southern or western exposure.

Thanks Tug ,yep the usda says zones 4-9 so here is pretty covered.Ime south west facing aspect to the rear so get the sun all day when it shines, spring rain is on the up .My soil is pretty rich so the sandy soil is useful to know.Thanks.