Specialists such as Silk Tree at Wheatley sell bare-root, which are only available late winter/early spring, same as specialist apple nurseries.

I would carefully research the variety you plant, because growing something that more often than not fails to ripens its fruit, or only gives you a few very small grapes, is rather disappointing. That's likely what you get if you buy whatever it is your local garden centre has for sale. Is the vine Aldi are selling even labelled with a variety?