Although I am just an amateur gardener I would say that you could plant the hedges by the end of this month. The general time to plant trees and hedges, including bare root, is around this time of the year.
Try Dulwich Plants and Pots next to North Dulwich Station. They sell honey which is produced from the hives across the other side of the railway lines very close to their nursery. I have bought honey from there many times and it is very nice.