O.K., pay attention class......
The satellites in question are in what is known as geostationary or geosynchronous orbit, all directly above the equator and at a altitude of approx. 22,000 miles. At this distance the speed of the satellite matches the rotation of the earth, completing one orbit per day, and thus from any one spot on the earth the satellite always appears to be in the same direction in the sky. This ring around the earth 22,000 miles above the equator which gives geostationary orbits is known as the "Clarke Belt," named for science-fiction writer Arthur C. Clarke who proposed the idea in the 1940s.
Now it comes down to basic geometry. From any point in the northern hemisphere, the part of the Clarke Belt which can be "seen" by a dish forms an arc with its high-point due south and the ends disappearing below the horizon toward the east and west, like this:
Thus all of the satellites you can receive will lie somewhere along the arc, so you don't need to able to "see"
all of the sky with your dish, just that part of it which contains the Clarke Belt (or as much of it as you can manage).
The angle of elevation for the peak of the arc depends upon your own latitude. For example, both Malmo, Sweden and Palermo, Italy are approx. 13 degrees East of Greenwich, and thus some of the Eutelsat satellites at 13 deg. E will be due south from both locations (the satellites themselves, being in geostationary orbit over the equator, are actually 22,000 miles directly above the Congo in Africa).
However in Malmo the high, due south point of the arc is only 27 degrees above horizontal whereas in Palermo you would need the dish elevation set to around 46 degrees. These are the highest elevations needed from these two latitudes for aiming due south.
As you can see from the diagram, as soon as you move the dish away from due south the elevation is reduced correspondingly. For example, parts southern Scotland are on about the same latitude as Malmo, but to receive the Eutelsat cluster at 13 deg. E you now need to turn your dish azimuth to about 160 degrees, or 20 deg. to the east of south. Now the elevation is reduced to 24 degrees rather than the 27 deg. at Malmo.
If you lived right on the equator, your arc would extend from due east to due west with its highest point directly above you, e.g. from a point at 13 deg. E in the Congo you would point your dish straight up for the same Eutelsat satellites.
Clearly then, at higher latitudes you not will not only have your high-point of the arc at a much lower elevation, but a greater portion of the whole arc will also be much lower in the sky. Thus city and valley dwellers in more northerly locations are likely to find it harder to find a dish location which gives as clear a sweep of the Clarke Belt than somebody located farther south. This becomes more of a problem as you try to pick up satellites near to your horizon where you will be aiming relatively low and might have buildings and other local features in the line of sight. Rural dwellers on the Prairies are in an ideal spot, of course!
So in practical terms, the first thing you need to look for in the U.K. is a spot which will give your dish as good a view of the southern sky as possible. It's inevitable that some obstructions will exist, but with a little luck and planning you may be able to arrange the dish such these dead spots don't lie on a part of the Clarke Belt which interests you. Obviously as the exact azimuth and elevation for any particular satellite depends upon your own latitude and longitude, that can only be determined by looking at each site individually.
By the way, if you live in the southern hemisphere just substitute "north" for "south" in the above descriptions. South of the equator you will get a similar arc with its high point due north.
Hope this explains it a little better. Class dismissed!
