Just to give you all a little follow up on how I got on with my Magnum cider, it tasted pretty good (what little of it I got to taste). I went on holidays after bottling it and left it in the care of my father. When I got back the cider fairies had visited and most of it had mysteriously vanished. I found the flavour to be more like an English cider rather than the Bulmers/Magners that you get here; there was more of a bite to it. It also seemed to be very strong compared to over the counter stuff. I drank a litre bottle of it one night and I found myself a bit giddy (and I'm no lightweight).
So now that all of my first batch has been consumed I currently have another bubbling away that should be ready for bottling on Sunday or Monday. Then next weekend I plan on starting a batch from my own apples. I don't have a clue how that will turn out or even how much juice I will get from 2 trees.