29-01-15, 05:03 PM
You're not giving yourself the best signal with a loft aerial and booster. A rooftop aerial and a quality downlead (CF100 or better) will probably help.
Crystal Palace looks like the best transmitter for your area, make sure you're aimed at it reasonably accurately with a group A aerial.
To know who to sue you'll need to find the source of the interference. It might be worth finding out whether your neighbours have the same problem.