To watch Sky you will need a min 1.5mtr dish get a H/H mount with that you'll get most of the movies and loads of other film and sport as well, for Itv and other's on a good day you will need a min 3mtr dish depending where you want it put. I use anything from a 80cms dish to a 3mtr dish and get loads of English channels but it's best to get a H/H system as there are loads of channels out there you don't have to pay to watch.
Hope this help's