The "No signal" message generally means a physical problem, which can be as simple as re-scanning the transponders, as the channels have moved frequency, to a dish mis-alignment, LNB failure, or just a loose connection.
The fact that you're receiving some channels, from the same satellite, seems to point to your dish being aligned, although you haven't mentioned your signal quality readings.
I would advise you check the FTA, Free To Air, channels, both Horizontal, and Vertical, as a faulty, failing, LNB can cause you to lose one polarity, and still view another.
If your signal quality readings are good, on both Horizontal, and Vertical, FTA channels, then a simple re-scan should solve the problem, providing your information is correct, using a 1.1M dish, in the UK.