having a look in fly sat beams... except the "2G" beam which is in a very high level, the others need about 70-80 cm "clear" dish (i mean straight center 28.2). anyway you can "forget" the uk beams.
now... for receiving both satellites, i suggest about 1m dish, and center about 19.2 -21,5 (to have a clear receive about 80cm in both satellites).