Thank you to all for your help. Wandering around with my ipad seems to have given me seamless coverage now. The signal starts to drop the goes back up to three bars when, I guess, it's logging on to the nearest and strongest signal.

Point noted about auto selection. Won't really be able to test until I have loads connected? That will be Xmas when the full family descend upon us. If it does become an issue, I have four wifi points, any suggestions on channels I should choose?

Thank you again to everyone for invaluable help.

I've installed the two Devolo WAP homeplugs, and, in conjunction with the Super Hub, the wireless signal seems to be fairly adequate throughout the 23 rooms of the house of the charity for whom I'm doing this work. But We Shall See when the reports come back!

If things go odd when lots of people around, check that people have remembers to turn off the hotspot function on their phone