
I have a similar problem except I am viewing through cable. When I tried to connect my roof aerial for some reason it has died.
I live in a hollow with a big hill that stops signals so you cannot use an internal set top aerial.
I suppose I could pay to have a new aerial (only had the old one put up 8 years ago), but I don't want to have to drill holes and put cables into the bedrooms and the dining room.
Is there not a wireless solution like you have with routers for the computer so that only one cable is needed and the rest can be run wireless. As you have found the assistants in shops selling TV's seem to know didllly squat about aerials.