Thanks for all your replies, I live in mid-Wales, it was -20c here last year, I did have an Escallonia and an evergreen Viburnum, in the garden both of which did not survive the cold winter. The evergreens that I know grow well here are, Holly and rhododendrons.

For the hedge I am going to use JC van tol holly and golden van tol as the spinless varieties, along with some green and variegated spined holly to add different leaf textures to the hedge, with berberis and cotoneaster, if it will take the cold.