You've had one, and please don't 'chase' as this is a customer to customer forum and people will post when they have something to add. The only BT staff are the mods who don't necessarily read every thread.
Sorry to have chased it seems our messages crossed!! It's so much the house is big but it's an 450 year-old cottage with thick stone walls but recently wired to current standards. As to your last suggestion I'll stick to the devices I have for the moment and try to get them to work.
Your advice, suggestions and patience from you both are much appreciated.