Hi Jenny have you tried the RHS plantfinder?
That lists (for Abies koreana 'Silberlocke')
Cooling's Nurseries Ltd
Sevenoaks , Kent, TN14 7NN
Details
Lime Cross Nursery
Hailsham , East Sussex, BN27 4RS
Details
Perryhill Nurseries Ltd
Hartfield , East Sussex, TN7 4JP
Details
The Potted Garden Nursery
Maidstone , Kent, ME14 4NH