In article , Chris Boulby
writes

Does one really need to protect grape roots in winter? If so, what
from? I know they grow successfully in the Niagara fruit belt in
Southern Ontario, where winter can be both severe (down to -20C at
times) and sometimes quite wet if the snow thaws. The main reason for
growing grapes here under glass may be to give them more summer warmth
to ripen them, but others may know more than I do about this subject. I
have grown them completely outdoors when I lived in South Yorkshire, and
even managed to ripen them. We only got three bottles of wine from our
one vine :-)

Yes, grape vines will survive UK winters outside and live to grow again.
They will often flower and begin to bunch up too, but unless they are a
hardy variety bred for that purpose (often with sharp white berries),
they will seldom produce a satisfactory crop of fruit. There are some
commercial vineyards in S& SW UK where local conditions permit.

We have prolific crops from three varieties of vine in greenhouse and
poly-tunnel. They all propagate well from cuttings, but none have ever
done much more than survive outside.
--
Alan & Joan Gould - North Lincs.