Your malling leo raspberries are summer fruiting variety and you are correct in your understanding and will have to wait till next year for fruit. If the canes are long you could leave them and see if they fruit - its a gamble. To get fruit this year try an autumn variety ie Autumn Bliss.
Prune Summer Fruiting canes immediately after harvest - do not cut out any new non fruiting canes.
Prune Autumn Fruiting canes in late winter.