I want to wall mount a TV and have no cables visible - I want to run the cable from the TV, into the internal plasterboard wall, up vertically, into the loft and across to another room. The entry into the other room is fine, but I'm not sure how I can route the wire internally on the wall we hang the TV on. It seems there are horizontal wooden supports in the way (which I assume are structural, but have no idea).

I only need one cable (from Samsung One Connect Box to TV) so do not need power, ethernet etc.

The house is a single storey new build a few years ago, and we have roof access (altho harder near the edges of the house due to the roof pitch).

Would a builder / electrician be used to doing this and be able to do it without removing most of the wall? Or is there a magic tool for DIY?!