if your wall is plasterboard there should be a void between it and the wall. cut a hole behind the tv. carefully remove the skirting board and run the cables from where they are now to the bottom of the wall.drop a string down the in side of the wall with a small weight attached. attach cables to string and pull up to tv. if the plaster board comes down to the floor you can cut a slot along the bottom as it will be hidden by the skirting.