I haven't had Hornsbys in years. Now that I'm in Vermont, they basically only sell Woodchuck. I do remember they taste very similar.
The question is, what about it do you want to replicate? If you just want a sweet cider, there is a couple ways of doing it. Do a search as there are many threads on the topic.
Oh and don't listen to the naysayers of Hornsby. It tastes very good and there is no reason not to try to make a similar cider. From my personal experience, you won't be able to replicate much. Unlike beer, which uses ingredients that are very replicate-able, cider largely depends on the mix of apples and good cider apples are hard to find. The nice thing about cider is that whatever you end up making, it will taste incredible.