Leylandii is a nightmare - because it is the fastest growing hedge! Once it gets to height you are going to have to maintain it as it will still be trying to grow 3 feet a year ...

... I would recommend Thuja plicata (atrovirens would be my choice).

But having said that I have never been able to grow conifers from cuttings

Might be worth looking for Rooted Cuttings on Google? For things I've looked for, in bulk, they work out around 10p-20p each, rather than £££ per plant