Thank you for kind advice. I realise that it would be easier to have the dish on the ground but not possible for me. Meanwhile, all my channels, except Channel 5, have been back since I got home in December, in spite of heavy rain and wind so it is still a mystery as to what happened.
I had another think here. Both Sky and Freesat download firmware updates to your box, usually during the night. If your box was off while you were away I mean off and not on stand by, then it would not have had any updates regarding channel frequency changes and so you would get blanks on any channel that had changed. The first night you left it on standby, it would have got the updates and everything would be working again next day.
The next test is 2E. It has been parked at 43degE for prolonged tests but started its drift westwards a few days ago. Monitoring its position & speed of drift, it should be in its right position at 28.2E in about 10 days. So expect a bit of bother at the end of the month. That will be the time to tweak the dish first. If that does not bring back any missing ones, then it will mean a bigger dish, provided those already with bigger dishes say they have a signal.
Astra's predictive map showed a useable signal in Lyon (60cm dish) so I believe we shall be all right on S coast of France. Scandinavian and Southern Spain viewers might have serious problems.
And what you say about the French above is completely true. I live in a small village & although they moan about miscreants, they do not have anti-social problems on the scale of England. They maintain politeness and family standards that the English could do well to re-learn. I have had nothing but courtesy and friendliness, possibly helped by the fact that I insist on using my poor, but improving French and participate humbly in village life. I even went to the half a pig & legs of ham bingo.